Gamemaker 2 - "Unable to login - no network connection"

[steven_layton_sl]

We've just installed the Trial version of GameMaker 2 onto one of our network stations. When trying to logon with my account details I am getting a "Unable to login - no network connection" error message.

 

When I logon to GameMaker with the same details on a computer not going though the school firewall/proxy server it works.

 

Its either going to be a specific URL(s) or Port(s) that need unblocking. Does anyone know what they'll be as I'm having no luck with the realtime webfilter / firewall logs on the Smoothwall firewall/filter box.