How to find out which left-wing people are connected to yours Wi-Fi router? The easiest way is to turn off the Internet during rush hour and listen to what is happening around you in complete silence. The hysterical reaction of the neighbors will tell you the answer to this question. Well, seriously speaking, you can find out this information in the router settings and using special programs. How all this is learned, and most importantly, what to do with this information later, we will consider in this article.
Slow Internet may indicate that poor Wi-Fi connections have appeared. The network will begin to slow down, the speed will drop to a critical minimum, and none of the household members will be caught actively downloading files. But no particularly active actions are needed to restrict each user of the local network if this network is provided by a weak router. With this, and even with a slow connection according to the tariff, each of the network devices will receive its own minimum resource. And this can even be reflected in the speed of opening sites. Lovers deserve the balls right, but it’s unfair for those who pay for the Internet.
But where big problems than slow Internet or even hefty bills received under metered tariffs, uninvited guests can throw up if they turn out to be scammers, distributors of porn, wanted by members of extremist groups or other seekers of problems with the law. And with the help of our access point they will do their business.
You can detect the fact of a third-party connection to Wi-Fi if you temporarily disconnect all authorized devices from the network. The router indicator that continues to blink will indicate that wireless Internet someone is using it. The following will help you understand which equipment is currently connected to the network without our knowledge, and also take action against uninvited guests.
You can specifically verify that there are third-party connections to the Wi-Fi network using the router’s web interface. To do this, you need to enter the interface in the browser window, log in and go to the section where active wireless connections are displayed. Each brand of router has its own interface, moreover, different versions Firmware may be available for different model lines, so universal instructions here, by convention, there can be no speech. But, friends, I will show the principle of operation using the example of the TP-Link TL-WR720N model.
In the browser window, enter the IP address of the router; for TP-Link, as for many other models, it is 192.168.0.1. Next, an authorization window will appear in which you need to specify a username and password. Again, for many router models the default is admin and admin, respectively. To view devices connected to the Wi-Fi network, go to the “Wireless Mode” section and click “Wireless Mode Statistics”. In my case, there is only one wireless connection - a smartphone. Using TP-Link firmware we will only see the MAC address of the smartphone.
Not much more information, alas, is displayed in the “Advanced Settings” section in the “List of DHCP Clients”, where all network equipment is listed. The router has detected the name of the computer connected via Ethernet. But the smartphone remained unknown to him.
Other router models may provide more information about connected devices. For example, determine the manufacturer or operating system. But even with such a minimum of information that TP-Link provides, the difference between the total number of wireless connections and the number of gadgets in your household will help you understand the very fact of Wi-Fi theft.
In principle, at this stage the investigation can be completed: the fact of theft has been established, then we proceed in the most simple method– change the Wi-Fi password. Or we install it if the access point was initially not password-protected. In the tested TP-Link model, this is done in the same “Wireless Mode” section, in the “Wireless Protection” subsection, in the “PSK Password” column.
For the average person, these measures will be sufficient. But our move will not stop more or less competent thieves, because the Internet is full of instructions for determining the password of other people’s Wi-Fi access points. Devices of persistent balloon lovers must be blocked by MAC addresses. And if there are several devices connected to Wi-Fi, you need to determine whose MAC addresses are.
How can you find out where whose MAC addresses are if the router firmware does not provide at least some identifying feature for network devices?
Option No. 1: You can find out the MAC addresses for each of your household devices using the functionality operating systems or third-party applications of used gadgets. And thus identify the Internet thief. But there is a much simpler method.
Option number 2: you can use the special Windows program SoftPerfect WiFi Guard. This and more convenient way determination of MAC addresses of network devices, and also a tool for preventing unauthorized wireless connections.
We don’t close the router’s web interface for now, we’ll come back to it later.
The simple SoftPerfect WiFi Guard program, which supports a Russian-language interface, provides a small but useful list of features:
Scans the network for connections, in particular wireless ones;
Detects third-party devices and signals their connection;
Provides information about MAC addresses and manufacturers of equipment connected to the network;
Keeps a history of all devices ever connected to the network since the first scan.
The program is downloaded from the developer’s website, there is a portable version:
https://www.softperfect.com/products/wifiguard/
You can use SoftPerfect WiFi Guard to monitor up to 5 network devices for free. This restriction is removed when purchasing a perpetual (!) license for 1,120 rubles.
How to use the program? We install it on the system or unpack the portable version. Let's launch. If your computer has several network adapters, including virtual ones, as those who work with hypervisors will certainly have, SoftPerfect WiFi Guard will launch with the settings window active and ask you to specify the required network adapter. In the list of adapters, select the physical one - the one that does not include the names of hypervisor programs.
We launch the scan directly in the SoftPerfect WiFi Guard window.
The program will notify you with the following notification about all detected smartphones, tablets, TVs and other equipment connected to Wi-Fi.
After which the window will display the entire list of network devices. The router and the current computer in the “Info” column will be marked, respectively, as “Internet gateway” and “This computer”. The router and the current Windows computer will appear with a green indicator, which indicates that they are authorized by the program by default. All devices connected via Wi-Fi will be marked with a red indicator. And this means that the program sees them as third parties. And they will continue to see it this way until we ourselves sanction them. In the “Manufacturer” column of each device we will see the manufacturer. For desktops, the manufacturer will be displayed as such a company motherboard.
In fact, in this way, based on the device manufacturer, you can determine which of them owns the MAC addresses displayed both in the router interface and in the program window. Of course, if it happens that an Internet thief has, for example, a smartphone from the same manufacturer as someone in the household, then he will have to look at the MAC address on the latter’s smartphone and use the exclusion method.
So, where whose gadget has been sorted out, now using the program’s context menu we can copy the MAC addresses of thieves for the blacklist or our household members for the white blocking list using a router.
But we’ll talk about blocking a little later, before we look at some more features of SoftPerfect WiFi Guard. Double-clicking on an unauthorized device will open a properties window where you can authorize it by checking the box that says “I know this computer or...”.
In this case, the gadget will receive a green indicator, and during subsequent scans the program will no longer display a message about it. By clicking the “All devices” button, we get a list of all computers, smartphones, tablets and other equipment ever connected to the network during the program’s operation.
In the settings section we can change the time period for scanning the network. If the preset half an hour is too short a time period, move the slider of the “Rescan the network every...” option to the left, to the desired value. Also in the settings you can check the option to run the program from the system tray. And if necessary, select the program to autorun.
Setting up a network connection in accordance with all instructions does not guarantee uninterrupted access to the Internet. The reasons why a network stops working are varied and not always obvious. Let's talk about what can cause an Ethernet connection to fail and how to fix it.
Hardware-related reasons:
Reasons related to settings:
If the connection is limited for certain applications, for example, only for the browser:
If the connection is completely absent, periodically disappears or loses data, start checking with the network cable. Make sure its insulation is intact and there are no kinks. Check the quality of fastening of the connectors.
If you are setting up the connection for the first time, make sure that the cable is crimped correctly (the conductors are connected to the correct contacts of the connector). Below are the crimping diagrams:
The check is only relevant if you crimped the cable yourself. Cables purchased in a store already with connectors rarely fail.
Next, check whether the network is connected correctly. The Internet connection can be direct (the provider's cable is connected to the computer's network card) or through a gateway (router or other computer). The method of switching and access settings can be found in the technical support of the provider.
When connecting through a router, it is important not to confuse the connection sockets: the provider’s cable is inserted into the “INTERNET” or “WAN” socket, and network cards of computers are connected to the “LAN” sockets.
If there is still no connection, check whether the Windows network driver.
After that, open the card properties through the context menu in Device Manager
and make sure it works fine.
Next, open the “Power Management” tab and uncheck the “Allow shutdown to save energy” option, otherwise the connection will be interrupted.
If, after installing the network driver, the connection is still limited, check whether there are any devices near the computer, router or network cable installation that create interference: cordless phones, high-power power lines, microwaves. Try to move your network equipment away from such places.
The Troubleshooting tool allows you to identify and eliminate the causes of various network failures in Winows 8. To launch it, click on the “Network” icon in the system tray and select the item of the same name.
If the problem is not automatically resolved, the diagnostic tool will tell you what caused the problem.
In this case, the cause will have to be sought and corrected in other ways.
If your Internet connection is limited or absent, it may be due to a failure of Windows network services. To check their operation, open the service management application:
In the service management program, check the operation of the following components:
If these Windows services are not running, the connection will not be created or will be limited to the local network only - no access to the Internet.
To configure autostart of network services along with Windows, open the properties of each of them (via the context menu).
Select Automatic from the Startup Type list. To start the service immediately, click the button of the same name in the “Status” section of the window.
This operation restores the state of network structures - Windows 8 registry sections where the Winsock configuration is stored. To reset, use the Windows console utility - netshell.exe. Accordingly, it is launched via the command line (as an administrator).
To reset Winsock and the TCP/IP protocol, run two instructions in the console one after the other: netsh winsock reset And netsh int ip reset.
After this, restart your computer.
To check the connection settings, enter the context menu of the Windows button (Start) and open the folder " Network connections».
Right-click to open the connection context menu and click “Status”.
The next window will display the main connection parameters:
To go to the settings, click the “Properties” button in the “Status” window. IN next window Check “IP version 4” in the list of components and click “Properties” again.
If the connection does not receive IP and other settings automatically, enter them manually. If your computer is connected to the Internet directly (without a gateway), check with your ISP for settings. When connecting through a gateway (router), one of the addresses in the local range to which the gateway belongs is assigned as an IP. For example, if the router address starts with 192.168.1, the connection address should start with the same numbers.
In the “Default gateway” field the IP of the router is indicated.
Information on disabling a third-party firewall can be found in its help.
There is no point in trying to reconfigure a connection on a corporate network that is limited by the administrator - it won’t work anyway. And if it is limited to the home, and this is definitely not the work of your loved ones, it is possible that a virus has entered the system. For the same reason, network access may be denied to individual applications. To solve the problem, scan your system with an antivirus and check your network settings again.
If the failure occurs in only one application, check the network access settings in it and the restriction rules for it in the Windows Firewall. If the source of the problem is not found, reinstall the program.
Question from a user
Good day.
Tell me how can I find out who is connected to my Wi-Fi networks, can't someone be connected to it other than me? (neighbors, for example). The speed just inexplicably drops every evening (I can’t even watch YouTube without lags), I don’t know what to do...
PS called the provider - they say that everything is fine with the network.
Good day!
Anything, of course, can happen, but more often than not, Internet slowdowns and lags are not due to the fact that a neighbor has connected to you and is pumping your traffic, but to more mundane things: the poor quality of the provider’s network (it’s just that everyone comes home from work in the evening and hangs up "channel - there are not enough resources), software errors and glitches in your OS, etc.
Now about how to see which devices and computers are using your router...
The easiest and most informative way to find out which devices are connected to the Wi-Fi network is to look at the router settings (web interface). Almost every modern router (in 99% of cases) has a tab in the settings that shows all active devices.
To help! How to enter the router settings (instructions) -
Most often, to enter the router settings, just enter IP 192.168.0.1 (or 192.168.1.1, 192.168.10.1) into the address bar of the browser. "admin" is used as the password and login.
For example, in my Tenda router there is a “Status” tab that opens by default (immediately when you go into the settings). In it you can find out the number of connected devices, the overall download and upload speed (see screenshot below).
Note: Depending on the router model and firmware version, your menu and settings sections may differ slightly. As a rule, you need to find the "Status" tab.
Connected devices (Tenda router) / Clickable
For detailed information about connected devices, you need to go to the “Bandwidth Control” tab: pay attention to the name of the devices and their activity.
Bandwidth control (Tenda router) / Clickable
If we talk about models of other routers, then, for example, in TP-Link routers you can see a similar tab in the “Wireless mode/wireless mode statistics” section. It is shown next to each device (you can immediately find out which device is the “neighbor”).
Another example below: in the English version of the firmware ( D-Link router) you need to open the "Status/Wireless" tab (in Russian "Status/wireless connection") .
In general, it is almost impossible to provide screenshots of all router models and firmware in one article. But fortunately, in almost all models the menu is identical (you can also use the technical instructions for your device).
Important!
If you notice that you have more computers (devices) connected to your router than you connected to it yourself, be sure to change the security settings.
Set a new password, make sure you are using WPA2 with AES encryption, enable MAC address locking, and disable WPS. All this is quite easy to do in the router’s web interface.
Instructions for setting up routers: ,
If you are unable to open the router settings (this also happens), then you can see who is connected using programs. True, in this case you will only be able to find out about the “extra user”... But in order to change the password or disconnect the “unnecessary” user from the network, you will still have to go to the web interface of the Wi-Fi router and change the settings...
Note: Windows application
Wireless Network Watcher - main window after scanning the network / Clickable
Free and portable (no installation required) utility for quickly scanning Wi-Fi networks. After launching, it will automatically “run through” the entire network and show all active devices (their MAC addresses, IP addresses, names, adapter name, etc. information).
By the way, the resulting list can be sent to a text file, HTML, XML, CSV and printed. It’s very convenient to then go through all your devices and do a mini-inspection to see if its MAC address matches...
Note: Android app
A simple and convenient application for monitoring Wi-Fi networks from a smartphone or tablet. In order to view all currently active devices on the network, go to the “Scanning” tab and click the button of the same name at the bottom of the window. After 10-30 seconds. the network will be scanned and you will see a list of devices. Easy and fast?!
By the way, Wi-Fi Monitor also has handy features: you can see the reception speed, upload speed, channels (which are occupied by you, which are occupied by your neighbors), find out the signal level and other necessary information.
I hope the situation has been clarified?!
Good afternoon.
Do you know that the reason for the drop in speed on a Wi-Fi network can be neighbors who have connected to your router and are taking up the entire channel with their surges? Moreover, it would be okay if they just downloaded it, but what if they start breaking the law using your Internet channel? Claims, first of all, will be addressed to you!
That is why it is advisable to set a password for your Wi-Fi network and sometimes see who is connected to the Wi-Fi router (what devices, are they yours?). Let's take a closer look at how this is done ( The article provides 2 ways)…
STEP 1 - enter the router settings (define the IP address to enter the settings)
To find out who is connected to the Wi-Fi network, you need to enter the router settings. There is a special page for this, although it opens on different routers - at different addresses. How can I find this address?
1) Stickers and stickers on the device...
The easiest way is to carefully look at the router itself (or its documents). There is usually a sticker on the device body that indicates the address for settings and a username and password for logging in.
In Fig. Figure 1 shows an example of such a sticker; to access settings with “admin” rights, you need:
Rice. 1. Sticker on the router with settings.
2) Command line...
If you have Internet on your computer (laptop), then you can find out the main gateway through which the network operates (and this is the IP address to enter the page with the router settings).
Sequencing:
Rice. 2. Command line (Windows 8).
3) Special utility
There is a special utilities for searching and determining the IP address to enter settings. One of these utilities is described in the second part of this article (but you can also use analogues so that there is enough of this “good” on the Internet :)).
4) If you can’t log in...
If you haven’t found the settings page, I recommend reading the following articles:
Rice. 3.TP-Link
Rostelecom
The menu in routers from Rostelecom is, as a rule, in Russian and, as a rule, there are no problems with searching. To view devices on the network, simply expand the " Device Information", DHCP tab. In addition to the MAC address, here you will see the internal IP address in this network, the name of the computer (device) connected to Wi-Fi, and the time spent on the network (see Fig. 4).
Rice. 4. Router from Rostelecom.
A very popular router model, and often the menu is in English. First you need to open the Wireless section, then open the Status subsection (in principle, everything is logical).
Rice. 5. D-Link who joined
If you do not know the password to access the router settings (or simply cannot enter them, or cannot find it in the settings necessary information), I recommend using the second method of viewing connected devices to your Wi-Fi network...
This method has its advantages: you don’t need to waste time searching for the IP address and entering the router settings, you don’t need to install or configure anything, you don’t need to know anything, everything happens quickly and automatically (you just need to run one small special utility - Wireless Network Watcher).
A small utility that does not require installation, which will help you quickly determine who is connected to the Wi-Fi router, their MAC addresses and IP addresses. Works in all new versions of Windows: 7, 8, 10. The downside is that there is no support for the Russian language.
After launching the utility, you will see a window like in Fig. 6. There will be several lines in front of you - pay attention to the “Device information” column:
Rice. 6. Wireless Network Watcher.
In general, extremely convenient thing, especially if you haven’t yet understood the intricacies of your router’s settings too well. However, it is worth noting the disadvantages of this method of identifying devices connected to a Wi-Fi network:
This concludes the article, I will be grateful for additions on the topic of the article. Good Luck!
In a pop-up window on the computer monitor, the message “Network cable is not connected” appeared, the LED on the network card did not light up. You insert and remove the RJ-45 plug in the hope of poor contact in the connection and realize that the cable is faulty. If you do not have a separate network card installed in your computer, and the network cable plug is inserted directly into the motherboard, the LED will not light if the connection is disabled by software.
Nowadays, a twisted pair network cable is often first connected to the router, which sometimes freezes. Therefore, first of all, you need to reboot the router. To do this, just disconnect it from the power supply for a minute and then turn it on again. It is quite possible that access to the Internet will be restored after this.
A shutdown can occur without your direct participation, for example due to unstable network voltage, running unlicensed programs or a virus. To check in Win XP you need to go to: Start / Settings / Control Panel / Network Connections and make sure that the connection is connected. Less often, but it also happens, the network card driver does not work correctly. You can check: Start / Settings / Control Panel / System / Hardware / Device Manager / Network Cards. There should be no warning signs.
Network cards very rarely fail; this sometimes happens after a severe thunderstorm. You can check the functionality of the network card by connecting it to a known-good line or installing it in another computer, not forgetting to install the driver for it. Sometimes it is possible to get a network card to work by moving it to an adjacent slot on the motherboard.
Call to technical service the provider will help check the functionality of the line on their part. If everything is in order with the computer and the provider, it means that the twisted pair cable has failed and requires repair. You can, of course, call specialists and wait, but if you wish, it is possible to diagnose and repair the twisted pair cable yourself.
The most likely malfunctions of the twisted pair cable are:
- complete break of one or more wires - occurs often;
- short circuit between conductors of one twisted pair or between wires of adjacent pairs - less common.
IN search engines People often look for the answer to the question: “a program for testing twisted pair cables.” On a computer with installed system Windows already has a program that displays the message “Network cable is not connected” if the twisted pairs in the cable are broken or shorted. You will have to look for the location of the break or short circuit yourself; there is no program that would indicate the exact location and cause of the malfunction. There are special testers for this, for example MicroScanner Pro.
It’s another matter if there is a connection to the Internet, but it is not stable or the download speed has suddenly dropped. For monitoring network traffic there is an excellent free program, more precisely a utility called Network Traffic Monitor.
It allows you to measure data transfer speed in real time, observe changes in speed over time, save data on a hard drive, rubber windows, extensive customization options and many other useful services. Supports many languages, including Russian.
Installing the program on your computer is simple, just run the EXE file and press the confirm button several times. Network will automatically be added to startup and will monitor and save all data. To display any of the windows on the monitor screen, just right-click on the tray icon and select the desired window. Network Traffic Monitor is the best utility for analyzing and diagnosing network quality that I came across during my search. I have tested the functionality of the Network Traffic Monitor program with Windows HP and Windows 7. Download Network program Traffic Monitor with one click of a mouse button you can from my website.
To check twisted pair cables with knowledge of the matter, it is advisable to represent electrical diagram connecting a computer's network card with a twisted pair cable to other devices, a hub, a switch or another computer. The figure shows a diagram of a section of the network connecting a computer to active equipment, a hub or switch.
To check the twisted pair cable, the part of the network card or hub circuit to which the RJ-45 twisted pair cable connector is connected is of interest. As you can see, each pair is connected to the transformer in a symmetrical circuit (a tap is made from the middle of the transformer winding, which is connected to a common wire, sometimes through a resistor or capacitor). Thanks to this connection, all induced noise in the cable arrives at the input in antiphase and is mutually destroyed, while the useful signal arrives in phase and its magnitude does not change. The transformer circuit has another advantage: it protects active equipment from short circuits and entanglement of wires in a twisted pair cable when connected.
Some people have a question, what shape and scope does the signal in twisted pairs have? The photograph shown is an oscillogram of the information signal. On twisted pairs, both Rx and Tx signals have approximately the same shape and a swing of about two volts. The signal is transmitted via one pair, and received via the second, which is why two pairs are needed for communication. If one of the RJ-45 connectors of the twisted pair cable is removed from the equipment, signal transmission automatically stops.
Theoretically, the twisted pair signal should have rectangular shape, but since there is capacitance and resistance of the conductors, the signal shape is rounded. For this reason, the distance between communication points is limited, usually no more than 100 meters. The 2 V signal is not dangerous to humans, nor is a short circuit between pairs dangerous to network equipment, so you can troubleshoot a twisted pair cable without disconnecting it from the network. The network card, switch or hub will not fail.
There are several ways to find a break in a twisted pair cable: external inspection, continuity testing with a multimeter or pointer tester, and folk methods.
Checking a UTP cable should begin with an external inspection of the cable along its entire length, Special attention you need to pay attention to the quality of crimping in RJ-45 plugs. If crimped carelessly, the conductors may not be inserted into the plug all the way, and the contact will be poor. Or the conductors overlap with each other at the point of fixation (this happens with the green pair, since its conductors are crimped at a distance of two contacts) and the twisted pairs can short-circuit in this place. If a visual inspection does not reveal a fault, then it is necessary to test the twisted pair cable.
If you had at your disposal a modern cable tester with an LCD display, for example, MicroScanner Pro, which allows you to determine not only the type of defect in a twisted pair cable, but also its location, or at least a homemade LED tester, then no questions would arise. However, in everyday life you have to make do with improvised means.
The easiest way to check is to test the orange and green twisted pair with a pointer tester. To do this, you need to remove the RJ-45 plug from the computer's network card. Next, with the probes of the tester turned on in the resistance measurement mode, first touch the orange and white-orange conductor of the twisted pair. The tester should show a resistance of 1-2 ohms, then to green and white-green. The resistance should also be 1-2 Ohms. The polarity of the tester connection does not matter. Next, the resistance between the orange and green conductors of the pair is measured. It should be more than 100 ohms, usually equal to infinity. If the measurement results correspond to the above values, then the twisted pairs in the cable are working.
Here is another method, more complex, but reliable and indispensable if the twisted pair network cable being tested is not connected to the equipment. You need to bring the ends of the cable with RJ-45 plugs into one place and ring the conductors. It is necessary to set the switch on the device to the resistance measurement position and, according to the diagram, check the integrity of the conductors and the absence of a short circuit between them.
The photo shows a twisted pair cable crimped into an RJ-45 connector according to color-coded option B.
The end of one probe of the device is touched to the contact of one RJ-45 plug, and the other probe is touched to the contact of the same name of the second plug. The resistance should be zero. The wires of each color are called in turn and each wire is checked to ensure there is no short circuit with any other. The test for short circuits is carried out on one plug. To do this, one end of the probe is connected to contact, say number 1, and the second in turn to all the others. Next, the probe is connected to pin 2 and in turn to 3, 4, 5, 6. Since only two pairs are involved in signal transmission (orange and green, plug contacts 1, 2, 3, 6), you need to pay attention to them when checking Special attention.
But it is not always possible to connect the UTP cable connectors to one point. In this case, it is difficult to do without additional devices. Of course, you can extend the end of the tester probe to the entire length of the cable and perform the test together, or cut off one of the RJ-45 plugs, strip the wires and twist them together in pairs. But it is more expedient to make a simple device from an RJ-45 socket, short-circuiting the pairs in it with pieces of conductors with a diameter of 0.5 mm or resistors, as shown in the photo. It is better to use resistors, as this allows you to check not only the integrity of the twisted pair conductors, but also the presence of a short circuit between them. If the measured resistance value is zero, and not the value installed in the socket, it means that the conductors are shorted together. It is better to take different resistor values for twisted pair jumpers, for example 50, 100, 150 and 200 Ohms. Then the measurement results will be more informative.
The RJ-45 plug of one end of the twisted pair cable is inserted into a socket with jumpers, touching the tester probes to the contacts of the second plug, and checking each twisted pair in turn to ensure there is no short circuit between adjacent pairs using the technology described above.
Thanks to different resistance values, it is easy to check the correct crimping of twisted pairs when checking a newly manufactured cable. If any pairs are swapped, then the magnitude of the resistance will immediately show this. For example, if, when checking the orange pair, the multimeter shows a resistance of 100 Ohms instead of the required 50, it means that instead of the orange pair, another pair is crimped into contacts 1 and 2 of the RJ-45, or the cable is crimped in a different way.
It is very inconvenient to check a twisted pair cable by touching the RJ-45 plug. If there is a free RJ-45 socket available, the measurement conditions can be improved. Insert the other end of the cable into the socket and take measurements by touching the probes to the contacts inside the socket.
Based on the results of the inspection, a decision is made on further actions. If the orange or green pairs are broken or shorted, then you can replace them with one of the unused ones, brown or blue, if they are working. To do this, you will first have to cut one plug and ring all the pairs again, then the second one and re-check the pairs, since a break or short circuit may be in the plugs themselves. Short circuits occur at the point where the cable is clamped by the clamp in the plug when the wires are improperly prepared. Break if the conductors are cut when cutting the outer sheath of the cable. This is where they often break. If, after cutting the plugs, all pairs turn out to be defective, you need to more carefully inspect the cable along its entire length; if the damaged area cannot be detected, you will have to replace the twisted pair cable with a new one.
If you don’t have a tester or multimeter at hand, you can check the serviceability of the twisted pair cable without them using the proposed method below. It is necessary to cut off 10-15 cm pieces from the ends of the cable along with the connectors. Release the ends of the cable from the sheath by 5 cm and remove the insulation from each wire to a length of 2 cm.
In a small container made of dielectric material (glass, plastic, plastic bag) pour some water with dissolved in it table salt based on a quarter of the volume of salt from the volume of water. The more salt, the better. Salt is added to water to reduce its electrical resistance. Immerse all conductors of one end of the cable in a container with solution. You can immerse each twisted pair one by one. The distance between the twisted pair conductors should be minimal, but they should not touch.
Connect the twisted pairs of the opposite end of the cable in series to the poles of any battery or power source with a value of more than 3 V. If the salt concentration in the heated water is very high, 1.5 V will be sufficient. This voltage is produced by any AA battery, for example from a remote control remote control TV. A battery from cell phone, its voltage is about 3.7 V. A battery from the motherboard will also work, it has a voltage of 3.2 V. If you have a resistor with a nominal value of 50-100 Ohms, it is better to connect the battery through it, for protection in case of short circuit of the twisted pairs. The polarity of the connection does not matter.
The telephone network can be used as a power source. The voltage in the telephone network is about 40 volts and the current is constant, limited at the telephone exchange to 40 mA. This connection is safe for humans and the telephone line. This option is convenient to use if you need to supply voltage to a twisted pair cable in a hallway where there is a telephone box nearby.
Anything is suitable for testing. Charger from a cell phone, USB port of a computer, there is 5 V at the outer terminals. It is not permissible to connect to USB without a current-limiting resistor; you can damage the computer. To test twisted pairs, a current of 2 mA is sufficient.
After applying voltage, the following picture will be observed at the opposite ends of the twisted pair, which are in water.
As you can see, on the conductor that is connected to the minus (cathode), small white bubbles of hydrogen are released, and on the conductor connected to the plus (anode), yellow-green bubbles of chlorine are released. It is obvious that the pair is fine and there is no short circuit with other conductors. In the event of a short circuit, depending on which wire, white or yellow bubbles also came from the other wire.
If damage is found, then you can finish checking the twisted pairs and replace the faulty twisted pair with a blue or brown one. For example, when checking twisted pairs, a break was detected in the orange pair. Then connect the orange pair coming from the connectors to the blue pair of the cable. The connection technology is described on the page “Extending twisted pair cables”.
Of course, it is better to crimp the cable with new connectors rather than splice it. Or crimp using the old method, described on the page “How to crimp an RJ-11, RJ-45 plug onto a twisted pair cable.”
If the orange and green pairs are ok, and you don't want to bother with crimping the connectors, you need to check the cut pieces of cable with the connectors. To do this, all colored wires of twisted pairs, stripped of insulation, are twisted together and white and colored wires separately.
The connector is immersed in a saline solution to such a depth that the contacts are completely submerged in water. Twisted wires are connected to the battery.
On four of the eight contacts, white bubbles should form one after another. When you change the polarity of connecting the battery, bubbles should form on the contacts on which they did not appear before and also strictly after one. Deviation from this immediately indicates a malfunction. For example, if there are no white bubbles on one of the contacts, then the wire is broken; if there are no white bubbles on any contact, then there is a short circuit between the conductors. To clarify, you can perform individual testing of pairs by unwinding previously made twists.
Depending on the results obtained, you will have to crimp or splice the wires.
The cable is prepared as described above, only the container with the saline solution is replaced with half a potato. Each pair is stuck sequentially into the potato to a depth of 1-1.5 cm. The distance between the conductors should be minimal.
As you can see in the photo, the wire that is connected to the positive terminal of the battery turned green around the wire, and white foam appeared around the negative terminal. When the wires are removed from the potato, you will notice a darkening of the wire to which the minus was applied. If there are no changes in the cut of the potato, it means that the twisted pair conductors are broken or shorted to each other.
Just for fun, I poked the wires into the slice of an apple. Not so obvious, but it is obvious that the wires are in order.
Using the described twisted pair testing method, you can check wires of any type, cross-section and length.
