I don't know if people are still having this issue since this is an old post. I started getting this "Can't Authenticate" error about 2 weeks ago at my university. I came across this thread while trying to seek answers to my problem, I didn't find any that helped. I then started playing around with my settings. However, the thing that solved my problem was changing the connection to a WPA2 only setting.

Security method: WPA EAP
WPA EAP type: PEAP
Select certificate: None
EAP method: EAP MSCHAPv2
Username: <username>// without the domain
Password: <password>
Advanced Settings:
Proxy configuration: No proxy
Auto-retrieve IP address: on
Auto-retrieve DNS address: on
Manuall username: off
Require client authentication: off
WPA2 only mode: on <<-- This was what fixed it for me.

Seems like the router settings changed at my university without our knowledge. Only found the issue when checking for ways to connect to other OS, as every other OS were using WPA2-enterprise.

I hope this helps resolves the problems you may have as well.