I have 2 routers, 1 to provide internet, and one to provide a wireless network. The wireless router can be used to handle the internet by itself, but we had already established a network when we bought the wireless, and as only 1 person uses the wireless, it would be more bother than its worth to re-do the networks.

The problem I'm having is with port forwarding. In both of the router's settings, I've forwarded the port 6112 and 4050 to my computer (192.168.0.6), with both UDP and TCP enabled. I have an app listening on port 6112, and it's able to recieve incoming calls on this port, and it was unable to before I had enabled the port forwarding. However, this is the only app which can recieve incoming calls (on either port 6112 and 4050), no other app works.

When I have tried other apps (with the working one closed down), the port appears blocked and I am unable to recieve incoming connections. I use windows firewall, and currently I have it turned off.

Why is it that only this 1 app can listen, while others cannot. (I don't mean at the same time, though)

Any help would be appreciated