I have two PC's behind a comon internet router and one service running in another network that needs to connect with both PC's through internet using a specific port. To avoid dynamic IP issues I have configured NO-IP accounts in both computers and opened the port in their respective Windows Firewalls. My problem is that when I open the port in the router it only allows me to assign it to one of the computers, but not to both of them. Is there any solution to this?
I solved my problem using LogMeIn Hamachi and connecting my PC's directly using its VPN thus bypassing the router.
If both computers are on the same network, behind the same router, on the same shared IP address then you can't forward the same port to two different computers at the same time.
A lot of software with listening ports allow you to change which port they are listening on. Perhaps change the port on one of the computers to something else, and then forward the original port to the one computer and the newly chosen port to the other computer.
Check out sites like PortForward.com for some additional information and configuration help.
Hope that helps...