@Alexander Sack: Just to make it clear: I was running with the default configuration as far as /etc/network/interfaces and /etc/NetworkManager/nm-system-settings.conf is concerned.
The latter file looks like this:
[main]
plugins=ifupdown,keyfile
[ifupdown]
managed=false
As far as I can tell, that's how it should look like per default.
Also I do want NM to manage all my devices. Shouldn't this be the default? In any case, that's why I uncommented the lines in interfaces (they were added by the system, not myself).
@Alexander Sack: Just to make it clear: I was running with the default configuration as far as /etc/network/ interfaces and /etc/NetworkMan ager/nm- system- settings. conf is concerned.
The latter file looks like this:
[main] ifupdown, keyfile
plugins=
[ifupdown]
managed=false
As far as I can tell, that's how it should look like per default.
Also I do want NM to manage all my devices. Shouldn't this be the default? In any case, that's why I uncommented the lines in interfaces (they were added by the system, not myself).