Fix ethernet connection on Ubuntu server

Guides/os.md

@@ -20,7 +20,15 @@ Install iso with
 sudo dd bs=4M if=dsl-4.4.10.iso of=/dev/sdb status=progress oflag=sync
 ```
 
-## Ubuntu
+## Ubuntu server
+
+### Fix disabled ethernet
+
+Get interface name (e.g.: _enp2s0_): `ip addr`
+
+Edit the file `/etc/netplan/00-installer-config.yaml` and fix your interface name.
+
+## Ubuntu desktop
 
 Tips to set Ubuntu desktop.