The computer wasn’t connecting to the internet this morning with the nm-applet on the status bar saying network connections were unusable. Sigh. To be fair I had done a system upgrade of Arch Linux the day before, so I guess can this kind of thing Happens. When I ran:
$ nmcli c
…to check wi-fi connections none of was was showing a device, and when I tried to connect to my usual network using
$ nmcli con up [device-uuid]
I got an error that the connection couldn’t be activated because “No suitable device found for this connection (device lo not available because device is strictly unmanaged).”
I searched for the error and, as per an answer that was downvoted because it didn’t work on Ubuntu but worked for me, I added:
[ifupdown]
managed=true
to /etc/NetworkManager/NetworkManager.conf.
Restarted NetworkManager with
$ sudo systemctl restart NetworkManager.service
Worked instantly. When I checked connections with $ nmcli c again my usual connection had been assigned my main network device, and the nm-applet updated accordingly.