On the latest Ubuntu upgrade (last month), my network-manager stopped using the same saved connection automatically. It still opens an ethernet connection, but instead of using the one that I have defined (and marked as "automatically connect" and given it a priority of 20), it creates a new generic connection with every reboot. Since it doesn't have the DNS settings that I need, I have to manually connect to my saved connection.

I'm guessing there's something going on behind the scenes that perhaps I could change in a config file somewhere, I would be grateful if anyone could help.

The connection profiles are located in /etc/NetworkManager/system-connections/ and you can remove any that are unwanted of course.

The list of connections can be got via
What does the following report?
Is the ethernet interface being managed by NM? It won't manage any interfaces that are included in /etc/network/interfaces by default.

Thanks for that, ferrari. It turns out that I had a connection defined in /etc/network/interfaces, but that file also had a line "ensp0 default" (or whatever device the ethernet connection gets labelled as these days). My guess is that the upgrade stuck that line in there, probably I approved a merge without paying attention.

Derek

Ok, I assume all good now?

Yes, thanks so much!