...
If this succeeds, then the remote registry is enabled. If not you may need to start (or restart) the Remote Registry service.
Unix/Linux servers
Unable to connect to SSH
If you know your credentials are valid, but the appliance can still not connect, try logging in to the appliance and using SSH to connect directly.
An error of the form "Unable to negotiate with 203.0.113.0: no matching key exchange method found." implies that the target and your appliance do not have a shared key exchange method. (This happens with very out of date targets.)
If you get an error like "Connection closed by 203.0.113.0 port 22" it implies the SSH server on the target has crashed or is not running.