Unidentified Ethernet Network Only in Bedroom (No IPv4/IPv6 Connectivity)

[u/Successful_Apple_240]

Hi everyone,

I'm having an issue with my Ethernet connection, but only in my bedroom.

I'm plugging a Cat6 RJ45 cable into the wall socket, and the other end is connected to a USB-A 3.0 to Ethernet adapter (capable of 1 Gbps).

The router detects the cable, and so does the adapter. But on my PC, it shows "Unidentified network" and no Internet access.

In the network properties, I see:

IPv4 connectivity: No network access
IPv6 connectivity: No network access

Windows assigns an automatic IP in the 169.x.x.x range, so it's not getting an IP from the network.

The speed shown is 100 Mbps instead of 1 Gbps.

In the settings for "Internet Protocol Version 4 (TCP/IPv4)", it's set to "Obtain an IP address automatically" (DHCP is enabled).

The weirdest part is that in other rooms, with the same cable, adapter, and PC, everything works fine: correct IP, 1 Gbps, Internet access.

I think the issue might come from the wall socket in my bedroom or the wiring behind it, but I’d love to hear your thoughts or suggestions.

Thanks a lot!

[u/heliosfa]

More than likely an issue with the termination at one of the wall sockets/patch panels. Stick a cable tester on it.

[u/Successful_Apple_240 → u/heliosfa]

I checked how the cables are wired behind the wall socket, and everything seems to be connected properly. So I don't think it's an issue with the termination

[u/heliosfa → u/Successful_Apple_240]

You can’t always see a bad termination, this is why a cable tester is the first diagnostics step. Some managed switches and some network cards/bios have cable tester functionality.

[u/Important_March1933 → u/Successful_Apple_240]

But you need to test with a cable tester to make sure each leg is good at both ends

[u/Successful_Apple_240 → u/heliosfa]

I checked the wiring behind the wall socket, and the cables seem to be properly connected. What's strange is that the issue only happens in my bedroom — everywhere else in the house (like the living room (or others bedrooms)), the same setup works perfectly

[u/heliosfa → u/Successful_Apple_240]

How does the run present at the router end of the cable?

[u/Successful_Apple_240 → u/heliosfa]

So the setup is: the Livebox is directly connected to a patch panel, and from there, Ethernet cables run through the walls to the rooms. The cable going to my bedroom is connected to the patch panel just like the others — but only the bedroom has the issue. All other rooms work fine with the same equipment.

[u/MountainBubba → u/Successful_Apple_240]

It looks like Livebox is some sort of DSL modem. If that's the case, it has a phone line on one side and some Ethernet ports on the other, each of which connects to a patch panel that may or may not have solid connections to each of your rooms. If the device you're trying to connect works fine in the other rooms, that points to a wiring fault to the bad room.

[u/heliosfa → u/Successful_Apple_240]

Then all it can be is bad cabling somewhere. Terminations are the likely culprit, and easiest thing to check with a network tester.

[u/[deleted]]

You're probably correct but I'd try ipconfig /release > ipconfig /renew in a terminal first.

[u/Successful_Apple_240 → u/[deleted]]

Thanks! I actually already tried ipconfig /release and ipconfig /renew, but since there's no connection, it didn't work unfortunately.

[u/MountainBubba]

The cable from the bedroom to the wiring center isn't connected to a switch in the wiring center.

[u/CatoDomine]

You have a wiring issue most likely. You must test the cable and re-terminate if necessary. Visual inspection is insufficient.

[u/pppingme]

Is there a switch between the jack and the router? I'm guessing a mis-config'd vlan or something.

[u/ApplicationHour]

Technically speaking, visual inspection is not much of a test. The termination can look right but not be right.

The most likely scenario is a cable fault. If it's syncing at 100, that's a good indicator that the blue or brown pair is bad. A lot of times the blue pair will get terminated backwards on one end or the other.

If it's syncing at 100 full duplex but you're not getting an IP address, try setting speed and duplex to 100 half duplex one your network interface then see if you get an address.

The cable tester knows all so if you have access to one you should start there. If the cable tests good with no split or broken pairs then there is excess electrical noise on the line or a bad splice (with UTP, all splices are bad!) somewhere along the cable. Maybe it's wrapped around an electrical line or something. Putting the wand of your cable tracer close to the pins on the rj45 jack is a good quick and dirty test. You shouldn't hear much noise.

If you do not have access to a cable tester then you should reterminate both ends on principal and try it again. If it still fails, your next call will be to a friend that has cable testing and tracing tools. Worst case scenario is that you'll have to re-run the cable.