Can't reach DNS server

Question

I recently installed Proxmox server and add KDE Plasma desktop to its configuration. Everything worked fine for couple of hours but suddenly I lost my connection with internet. Of course I can connect to internet from other devices without any issue so I guess I messed something up in my system.

DHCP is disabled in my home network and my machine is working under 192.168.0.30/24. I can't ping my standard DNS which is 8.8.8.8 - Destination Host Unreachable. What's more I can't even ping my router under 192.168.0.1 (which is reacheable in the network on connected devices). I can reach my Proxmox VE interface through 192.168.0.30:8006 and some virtual machines under 192.168.0.31 and 192.168.0.32. The problem is I don't even know what I don't know. Can somebody lead a newbie a bit, please?

My lsb_release -a output (if it is neccessary):

Distributor ID: Debian
Description:    Debian GNU/Linux 11 (bullseye)
Relase:         11
Codename:       bullseye

I think the connection was lost directly after systemctl daemon-reload command

@Edit

ip route:

default via 192.168.0.1 dev vmbr0 proto kernel onlink 
default via 192.168.0.1 dev enx************ proto static metric 100 
192.168.0.0/24 dev vmbr0 proto kernel scope link src 192.168.0.30 
192.168.0.0/24 dev enx************ proto kernel scope link src 192.168.0.30 metric 100 

Answer 1

The problem is that you have two default routes, and in fact two different interfaces with the same IP address.

Typically what's supposed to happen is that your physical interface should have no IP address, and the host interface to your bridge should have it instead. So enx606d3cc9b999 should have neither IP address nor associated default route, but instead they should be assigned to vmbr0.

You need to try and identify where your physical interface is being configured and disable that configuration. (Has installing plasma installed a network service that hasn't noticed your interface is bridged?)

Installing plasma on your VM Host doesn't really make a lot of sense - you shouldn't be using it for day to day work at all; that's what the VMs are for. Keep the Host as sparse as possible.