How to diagnose a malfunction of the Realtek integrated network card?

Question

Iron

So.
I have a computer with an ASRock H81M-VG4 R2.0 motherboard. The network card is built on a Realtek RTL8111 chip. PCIE Gigabit LAN. Realtek PCIe GBE Family Controller - defined in the Manager.

Three days ago I received some critical Windows update - as I understood from the logs, just fresh drivers. And the network immediately fell off.
Writes an unidentified network. When diagnosing, it says that "The default gateway is not available."
What I did:
1. I rolled back the drivers from version 10 of 2017 to the 9th of 2015. On other completely similar computers everything works.
2. Rearranged drivers for new ones.
3. Restored the system from a restore point.
4. I downloaded the drivers specifically from the motherboard site.
5. Did Flushdns, ipconfig reset, sfc/scannow (didn't reveal anything) and that's it.
6. I downloaded the verification utility from the Realtek website - it did not reveal any problems with the hardware
.
7. Installed a static IP indicating the gateway, one to one as on other computers - silence.
8. I changed the cable from the computer to the outlet, cleaned the connector on the motherboard.
On the same cable and socket, any other device with a static or dynamic address connects to the network without problems.
In the network, all computers are connected to the switch, a DHCP server is running, and a router is already connected to it - which is a gateway.
LEDs on the Lan port of the motherboard: green is constantly on, orange is blinking.
On a computer there is software Trassir for video surveillance.
How else can you diagnose and solve a network connection problem? All brains have already broken.

Answer 1

Drno , nukler , Denis , Dmitry Spiridonov , Konstantin Tsvetkov , Yan ,
Thank you all. The network card worked.
I do not believe in miracles, but there are 3 sockets in the room to one switch:
1. My computer works, the problematic one is not, an unidentified network. I change the cable from the computer to the outlet - the same thing.
2. My computer is working, problematic, oh gods, it also worked. Same thing with the other cable.
3. The situation is the same as on the 1st outlet.
Despite the fact that, as far as I know, there are no prohibitions or glitches either on the switches or in the DHCP server settings. Almost bare settings without bells and whistles, port forwarding, and all that. Wonders)...
And yes, when booting in safe mode with network drivers, the network card did not work. Live did not have time to do.
Ping: Transmission failed. General failure - Related question

Answer 2

Try to boot from some boot disk, for example from this - nnm-club.me/forum/viewtopic.php?t=1252130 , thereby you will determine where the problem is - in hardware or in Windows / drivers

Answer 3

So-so advice:
Try to boot from any linux liveCD, I recommend SystemRescueCd .
If the console is not very good, then run startx in the system boot field, a graphical interface will open and you can figure it out there, since there is a graphical utility for configuring the network.

Answer 4

If it works from the boot disk, the problem is in the firewood.
If it does not work, the network has died.
Solving the wood problem.
Disable in services and never turn on Windows updates, disable driver installation from the network. Post the very first version of the driver from the website of the manufacturer of the motherboard or network card. Perhaps the driver from win 7 is suitable.
If possible, switch (reinstall) to the version of windows 10 ltsb ... there are a lot of versions on torrents. She is the least buggy.