We have a customer that is using firewalls between each of our servers on the farm.
We gave the customer specific description on how to configure Business Objects to be firewall friendly (according to the administrator guide) but sadly we still faced a critical error that caused our customer to wait for 10 min (I am serious) until getting timeout when trying to run a report (Error was "Request timed out because there has been no reply from the server in 600000 ms").
After working with the support and also running some port monitor we have found that apparently the dispatch of an action to RAS doesn't return the response on the same connection but rather opens a new connection from the RAS to the client SDK server (The client actually open some port for listening) - this is used as an async operation mechanism between SDK and RAS.
The port that is used by the client is selected out of a range of ports that is configured in the registry at HKEY_LOCAL_MACHINE\SOFTWARE\Business Objects\Suite 11.5\CER.
The default setting is on my XP are:
So you can see that the timeout is 600000 milliseconds = 10 min.
for our customer we set the range to be 5 ports and connection pool of 5 ports
In general don't forget that the first NIC that is used must be the one that is reachable to the RAS or else you could face the same symptom.
Hope that helped you (because I know by fact that this is not documented in Business Objects XI R 2 documentation)