I just got dosbox and I'm trying to get Descent to work in multiplayer

I just can't seem to get the 2 computers to connect in dosbox, I read the readme, I create a server on one computer and try to connect with the other to no avail. I have a router, but I'm typing the port number after the IP address. Shouldn't that be enough? I don't know what it means in the readme where it says "UDP port <port> needs to be forwarded"