Port closes for no reason (WinGate 4.5.2)

[bradley13]

We have a firewall that has run flawlessly for ages, using WinGate 4.5.2. Since it works so well, I'd prefer not to make any major changes.

We recently added an application that offers connections over port 50001 to the outside world. I've added a service in WinGate for this port, and everything works fine for a few hours. Then suddenly the port is closed. I have to remove and re-add the service for the external interface (causing "changes to the firewall") in order to re-open the port.

I'd appreciate any suggestion on how to fix this problem. Again, I'd prefer not to have to do a major upgrade ("never touch a running system").