Problem

You find that your gateway is blocking SSH connections and showing in the logs even though you have the ssh and ssh_version_2 protocols added to your rule.

message_info: SSH version 1.x is not allowed

Reason

On closer inspection when you look at the ssh_version_2 protocol object it says in the comment, Secure Shell, version 1.x block. This service object will block both versions. 

Solution

Add only the ssh service object to your rule, to allow both ssh versions through your gateway.