I've recently experienced a problem with connection to my server after rebooting it. Moreover, I tried to create a new one based on a snapshot I've made, but I wasn't able to connect to it too.
When trying to connect using web ssh user interface I see: We are unable to connect to the VM on port 22.
Connection trough command line gives this: ERROR: (gcloud.compute.ssh) [/usr/bin/ssh] exited with return code [255]