Proxmox Machine all of a sudden won't connect to the network, should I reinstall?

Hi All,

I have been using proxmox as an amaturer for over a year now and I am stumped on to get my machine to access the network

I’ll explain,

I have several VM on there where that I don’t want to loose so if I have to reinstall proxmox I was hoping there was a way I could back up all my files from the machine, by the way, I have access to the machine it’s says it’s hosting on the correct ip on the correct port, and it was, for about a month but now out of no where it cannot connect to the network and all my services went down.

as I am fairly new to proxmox and my machine a few years old I was hoping someone could help me with options to troubleshoot or back up the machine via the terminal so I can reinstall

FYI I have tried a different ethernet cable, several different ethernet ports, reset my router several times, modifed the DCHP setting to not send out the IP it’s configed on and I even bought a $40 ethernet adpator at bestbuy to see if it was the port and nothing, any ideas?

Let me know!


There’s too little to go on here, but barring something exotic, I think you could probably salvage this if we can track down the source of the problem. I’d start with the easiest places to look.

Two things that come immediately to mind are:

  1. Is there a VM that you’ve passed through the network adapter to by mistake? For example, if you’re running a router VM and passed through the wrong hardware NICs, that would cause problems.
  2. I’d love to see the contents of the /etc/network/interfaces file and also the output of ip route. I wonder if the default route was deleted somehow.

Sorry if you already know this much, but the first line of output from your ip route command should look something like: default via <your-gateway-ip> dev vmbr0 proto kernel onlink. If there’s not a line like that there, run ip route add default via <your-gateway-ip> and that will add the route immediately. If this was the problem, you’ll probably immediately have network access. To survive a reboot, you’d have to make sure there’s a gateway line for your vmbr0 interface in /etc/network/interfaces. That file should look something like this:

auto lo                                                                                                                                                                                                                            
iface lo inet loopback                                                                                                                                                                                                             

auto eno1    # The interface name might be different on your computer
iface eno1 inet manual

auto vmbr0
iface vmbr0 inet static
        address <proxmox-address>
        netmask   # This will depend on your network's subnet, but this the common one for a home network
        gateway <your-gateway-ip>  # Probably the address of your router
        bridge-ports eno1
        bridge-stp off
        bridge-fd 0
        bridge-vlan-aware yes
        bridge-vids 2-4094

So those are two easy things I’d check first and then expand the search based on whatever you discover.