I used to have to use different port for osx & windows 2000 using virtual pc. For osx try another between 49152 - 65535 for both connecting & listening through.
I am not sure how it works with both windows & osx, but I'd have thought the router would think of them both as being the same computer & same ip. My knowledge of networking is highly limited in how the numbers are given out, particularly for a single machine.

Are you trying to run them at same time? I do know that routers can get mucked up if two programs try to connect from same computer using same port even at different times & a reboot was necessary.

Is your router set to use UPnP for OSX? If not, then it will be blocked from incoming from whatever port it's set to.