So I installed the proxmox kernel in the hope it would better support a pcie SATA adapter in my system. No it didin't :))
Now my network graphs in the performance statistics show zero activity.
"ip link show" now tells me my interface is no longer called "enp3s0" but "enp4s0". Otherwise the system works fine.
In the network interfaces menu I see my nic with the old name and its static ip address.
I also see that I can add another interface based on the new enp4s0 name. I debate internally if I should do that and if it would break something. I decide to risk it.
I add a new interface with a different static ip. I close the page and restart the browser. I can now access the system with the new ip. Reboot. Go back to the interfaces menu and delete the old one wich was no longer showing graphs. Go to the new one and change the static ip to the previous one since I have rsync jobs which depend on ip address. Reboot.
Now my graphs are back. Hope this helps .