Ubuntu got many ways of configuring the network. It got ifupdown, Networkmanager and systemd-network. I found some instruction that said i must edit the interfaces file. That is the old way of doing it. My network settings ended up in a mess. When i entered something in interfaces, Network manager stopped handling that interface. Then i found something about netplan and YAML files. I removed ifupdown and used nm-connection-editor. I believe that is the best way.