When establishing an ssh connection to a remote machine it is possible to specify that this is done with X11 forwarding, which will enable X11 traffic to be passed back to the local server acting as an X11 server.
In version 2.7 a couple of checkboxes to this effect have been added to the appllication, in the access method section under the Device screen
And also in the Service Definition under the TCP/UDP service screen
To be able to successfully log in to the remote PAM appliance, the actual choice in the service definition needs to be in agreement with the setting for the default configuration of the Putty (or whatever ssh client application) you are using to connect to the remote machine as a service. That is, for instance, in the case of Putty, if X11 is checked for the TCP/UDP service, you would have to have as the "Enable X11 forwarding" checked or unchecked for Default Settings
In case the "Enable X11 forwarding" checkbox is not configured for the Default Settings in Putty, the choice in the TCP/UDP service under PAM does not cause the error to appear