Before reinstalling Mate 17.04, I was picking up three or four of my neighbor’s wi-fi signals, in addition to my own. I am now picking up nothing.
But this is something I tried, and it may be helpful. I rebooted into recovery mode and selected:
NetWork -------------- Enable Networking
This is what I got:
Trying to start NetworkManager…
Unknown group “power” in message bus configuration file
Could this have anything to do with it?