After the recent upgrade which adds the SSH-based integration, I often see it get disconnected after a few hours.
VS xamarin log:
Disconnected from Mac 192.168.11.5 (192.168.11.5)
Couldn't connect to 192.168.11.5. Please try again.
Disconnected from Mac 192.168.11.5 (192.168.11.5
I then try clicking the "debug" button as a means of re-triggering the Xamarin mac agent setup wizard, and after re-entering my credentials I get "couldn't connect". (But attempting to log in with SSH via Putty.exe works just fine)
Once I completely close and restart Visual Studio and re-open the solution, I'm able to connect for a few more hours.