Check the router configuration page (should be at the IP of the router, usually
http://192.168.0.1), somewhere under Advanced Settings you *should* see a section for port forwarding.
Enter in the external starting port (what you type in the browser) and the end port (whatever is in calibre) and the IP address of your computer.
It should look something like this I believe:
http://screenshots.portforward.com/r...Forwarding.htm