My office have a delphi application written by some programmers with a Interbase 6.1 database. We found out that sometimes the programs hangs, but do not know where and what?
After writing some extra code, we tried to update the database with approx. 7 clients with 100 updates, so the total amount of 700 will be updated. The updates were going fine, if we were on the local site!
When we tried the test over the internet with VPN (Netscreen firewalls), five clients "hang", so the updates were not correct.
When we've tried the same test over the internet without the VPN, the test was ok again.

Some extra info: Interbase 6.1, Several offices connected with VPN-internet.

Can someone help me with this?