VMs and LXC Containers Lose Internet Connection/Cannot ping gateway

BenGmuN

New Member
Feb 4, 2025
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Hi folks, brand new to Proxmox. I have one VM (Home Assistant OS) and one LXC Container (Plex based on Ubuntu 22.04 standard template).

Been having reliability issues with my router's WAN connection (incredibly short DHCP lease times enforced by my ISP resulting in a DHCP renewal timeout about once a day). When connectivity is restored, however, my VM and container can no longer ping the gateway address, nor can they access the internet.

This only appears to affect the VM and container running in Proxmox. Everything else is fine. The host (node?) can ping the gateway or external domain no problem. The VM and container can ping other devices on the network no problem at all. I can access the web interface for HA or Plex from within my network. It's as though something is blocking traffic between the VM/container and gateway. I have not consciously enabled any kind of firewall in Proxmox or my router config (again, though, this is only impacting my VMs/containers running in Proxmox).

If I reboot the container and VM, sometimes the issue is resolved. Earlier, though, I had to restart the node itself.

1738687461229.png

Additional info about my network:

Fibre comes into the building into the ONT (fibre modem thing) supplied by Swish Fibre (my ISP). The 10G port on the ONT is connected to my router, a TP-Link ER605. The router is connected to an unmanaged switch, and from there I'm connected straight to my Proxmox host, an HP Elitedesk 800G2.

No VLANs, nothing fancy. The VMs use the router IP as the gateway address - same as everything else.

I also encountered the below error when trying to reboot an affected VM:

1738686988743.png

Any advice welcomed.