We've run into issue after issue due to our firewall. Not just the ports being open but also the NAT (Network address Translation). For example, with stored processes, when the spawner fires up a stored process server it was referencing it using the servers internal IP address. The client (outside the firewall) couldn't see the server's internal IP address. There was a fix for this. But we still have a problem with Information Map studio when we attempt to access data from outside the firewall (can't test the map or create filters or expressions.)
One of my very knowledgeable colleagues suggested the following:
Make sure that that the workspace server is referencing the dns name of the firewall and make sure that the firewall is forwarding the port to the server.
An interesting response. Although I'm not sure I'm following you on 'dns name of the firewall'. We have to tell it the dns name of the machine that the workspace server is running on as well as the port. We can connect to the workspace server - hence we can build information maps. But when we attempt to add in a calculation, a filter, or attempt to test the map we get an error. Also we cannot use an info map from EG.