Aaargh - don't turn the firewall off, that will leave your PC unprotected.
You should just enable traffic on the correct port number.
First of all, look at the config of Broadwave to find out which port number it is configured to use. Some people use 85 or 88, I use a different one altogether.
Then, open that port on the PC running Broadwave. If it's Windows Firewall, you should open that and use Add Program or Add Port to make sure the correct port number is used.
You should now be able to connect from another PC on your local network, using your local IP address of the PC running Broadwave.
Once this works, configure the Router's firewall. You need to set up Port Forwarding, to define the port number being used, and also to which internal address the router should send connection requests from the outside world. The option might be called NAT setup.
Some routers also allow the external port number to be different from the internal port number, but that's not essential, the same number will usually do.
Now, you should try to connect from an external address, using your External IP address and the External port number.