I also contect to many servers through multiple firewalls,
Here is an article I once found:
Connecting to the iSeries Through a Firewall
Connecting through your firewall to the iSeries is really quite simple. The following ports must be opened for regular TCP/IP connection: 23, 449, and 8470 through 8476. However, if you are using an SSL connection, you need to open 992 for Telnet and then 449 and 9470 through 9476. Either of these configurations should give you Client Access support. The following is a table of information I grabbed from the IBM Web site detailing the ports:
Function Port SSL-Port
Server Mapper 449 449
License Management 8470 9470
Database 8471 9471
Database Queues 8472 9472
Network Drives 8473 9473
Printers 8474 9474
Remote Command 8475 9475
Signon Verification 8476 9476
Management Central 5555
Printer (BOS) 515
Management Central 5000-5020
Telnet 23
Ftp 21
Of course, if you want to use PC5250, you need port 23 for the Telnet access or 992 if you are using SSL communications. If you are using DRDA access, you will need to open port 446, along with the DDM port 447 or 448 if using SSL.
ODBC only requires the server mapper, database, and signon ports to be opened. The OLEDB provider requires the server mapper, database, remote command, and data queues ports to be opened. Hope this
Not sure if this is completely relevent, but we have connection to an iseries on VPN and we found we had to add the MUVPN route to the routing table on the AS400 in order to allow that user access to the system.
We have 2 machines, so we also have to make sure that both machine names appear on the PC lmhosts/host files.