I took an Acer C720 Chromebook and converted it to Ubuntu about 4 years ago. Runs great. It's been on 17.10 for awhile now no problems. On Sunday it ran fine. On Tuesday it can no longer connect to WiFi and I'm at a loss as to why. It's connected to our home SSID for years automatically. Now just tries and tries and fails. I can see every SSID in the neighborhood. Things that I have tried that have not worked:
-Connecting to the Hot Spot on my phone
-Restarted Network Manager
-Verified that NetworkManager.conf contained the line [device] wifi.scan-rand-mac-address=no
A lot of what I've read for fixes refers to older versions of Ubuntu or after an update to newer version. This problem just started out of nowhere. Worked yesterday not today.
Edit. Added 3/9/18
I tried this line to restart Network Manager but it didn't solve the problem either. sudo systemctl restart NetworkManager.service