Lost ethernet after changing home router

[Araneus]

Hello everyone!

I had a working setup of ProxMox working in home network, attached with the ethernet cable to my home router. Recently, the router had issues and was replaced with the new one. After that the computer with ProxMox doesn't see the network.

Any ideas where to dig to resolve this?

 

[Folke]

Hi,
could the subnet have changed with the new router? Like, from 192.168.0.0/24 to 192.168.1.0/24? When you set up pve, a static ip was set for the server, and if that subnet it's sitting in changed, it wouldn't be able to communicate with the rest of the network.
If that's not the case, could you please describe what you have already done to try to debug your problem, and what exactly you mean with "doesn't see" the network.

 

[Araneus]

The subnet is defaulted by this provider's router (192.168.178.0/24) and has not been changed with replacing the router.

By "doesn't see" I mean that PC with proxmox is not detectable by the router and does not appear in the list of Ethernet-attached devices.
I am not sure how to debug such a problem.

 

[Folke]

Do you have a display and keyboard, that you can plug into your server, or something like ipmi?
You can use the CLI to log-in and run ip a to get the current state of your network adapter.

 

[Araneus]

Do you have a display and keyboard, that you can plug into your server, or something like ipmi?
You can use the CLI to log-in and run ip a to get the current state of your network adapter.

Sure, I can't make screenshots, but took some pictures:

One is result of `ip a` command, and the second one is the content of /etc/network/interfaces file

 

[Folke]

I suppose you are not able to ping out, or ping the server from another device in your local network and can't reach the web interface via https://192.168.178.9:8006 ?
The config and output from ip a looks correct so far, could attach a laptop directly to the server and give it a static ip in the severs range and check if you can reach it?

 

[Araneus]

I suppose you are not able to ping out, or ping the server from another device in your local network and can't reach the web interface via https://192.168.178.9:8006 ?
The config and output from ip a looks correct so far, could attach a laptop directly to the server and give it a static ip in the severs range and check if you can reach it?

That is correct, if try to reach the PC from local network it is unreacheable:

Also, if I try to ping any IP from the server itself I receive the destination is unreachible. Also, it is not a problem of wired connection. I connected there my laptop instead of this PC and the network was reachable.
I can't connect another PC to the ProxMox PC since it has only one Ethernet port (it is not really a server, it is a mini PC I had)

 

[Folke]

Hm, Destination Host unreachable usually suggests, that there is something wrong with your routing config, or since you tried to ping the outside, the config of your router. Could you post the output of ip route and a ping to the gateway (ping 192.168.178.1)?

 

[Araneus]

Hm, Destination Host unreachable usually suggests, that there is something wrong with your routing config, or since you tried to ping the outside, the config of your router. Could you post the output of ip route and a ping to the gateway (ping 192.168.178.1)?

Here it is:


I'm not sure if this is due to router, because on the previous screenshots I see that there is no assigned IP to interface enp0s2 which supposed to be the Ethernet of this PC.

 

[Folke]

I see that there is no assigned IP to interface enp0s2 which supposed to be the Ethernet of this PC

Not quite right, enp0s2 is attached to vmbr0 which you could imagine as a virtual switch. The OS is "plugged in" into that switch. You can see that the bridge is using the correct interface in the config you send previously, the option is bridge-ports.
At this point, I would double-check all the physical stuff, is the network cable working, is the server/minipc plugged into the correct port of the router, sometimes not every RJ45 port is actually a LAN port...

To narrow down the problem, I would still plug a pc directly into the server, give it a static IP and check if you can talk to the server. This is just for diagnostics, not a permanent solution.

 

[Araneus]

Not quite right, enp0s2 is attached to vmbr0 which you could imagine as a virtual switch. The OS is "plugged in" into that switch. You can see that the bridge is using the correct interface in the config you send previously, the option is bridge-ports.
At this point, I would double-check all the physical stuff, is the network cable working, is the server/minipc plugged into the correct port of the router, sometimes not every RJ45 port is actually a LAN port...

To narrow down the problem, I would still plug a pc directly into the server, give it a static IP and check if you can talk to the server. This is just for diagnostics, not a permanent solution.

OK. Now stopped understanding anything. The router is connected to the wall socket in the room with a cable based on T568B pinout. From there it is connected to a target PC with a some Ethernet cable from store. In such configuration it was working previously before changing router.

Now:
- Booting ProxMox PC when connected to the wall socket have no internet whatsoever
- If instead of this ProxMox PC I connect my laptop (same cable, same wall socket) - LAptop (running windows 11) has internet like a charm
- If instead of ProxMox I boot any other Linux distro from Live USB on the same PC - no internet whatsoever
- Now, out of curiosity if it is Linux vs Windows issue. Wiped the whole ProxMOx PC, installed WIndows 11. NO Internet.
- Directly connected PC to the router with a long (10 m) cable. THere is internet! Worked like a charm.
- Connected ProxMox PC back to the wall socket - no internet. Connected there my laptop instead of ProxMOx PC - and it has internet.

I don't get it. BUt it might be a problem on the new router side.

P.S. Even more weird: if I connect the PC to Router via USB to ethernet adapter, it sees the internet.