proxmox: moving to linux and adding motherboard swap nic error

wiki/linux/proxmox.md

@@ -49,3 +49,19 @@ To use GPUs or other PCI devices you need to work with PCI passthrough.
 For documentation you can look in the [Proxmox wiki](https://pve.proxmox.com/wiki/Pci_passthrough).
 There is also an [article](https://www.reddit.com/r/homelab/comments/b5xpua/the_ultimate_beginners_guide_to_gpu_passthrough)
 on reddit, that focusses especially on windows 10 VMs with GPU passthrough.
+
+## Bugfixing
+
+### No internet after mainboard swap
+
+If you change the mainboard of your proxmox-virtual-environment it is possible,
+that the NIC changes.
+Find out the new interface name with `ip a`.
+After that get all occurences of the interface (`eth0` in the example) with
+`rgrep eth0 /etc` and change them to the new device with a text editor of your
+choice.
+It is possible that there are also files existing that need to be renamed.
+Find them with `find /etc -change '*eth0*'` and move them to the new name.
+After that `reboot` and the internet should be up again.
+(sources: [debian website](https://wiki.debian.org/NetworkInterfaceNames) and
+[proxmox forum](https://forum.proxmox.com/threads/upgrade-motherboard-reinstall.48630))