I've vnc-java running on an Ubuntu box, with the IP address 192.168.1.68, using port 5800 (because port 5900 is being used for normal VNC).

If I connect to 192.168.1.68:5800 using another computer on the network, I can use VNC fine.

Using www.whatismyip.com, I find out what my IP address from the outside world is, and if I go directly to that, I get to access my modem/router. If I try to navigate to that IP address, with ':5800' on the end, I get a "This web page is not available." error.

I have port forwarding set up in the router as follows:

Application Name    External Packet             Internal Host
                 IP Address     Protocol    Port    IP Address      Port    
VNC                  ALL        TCP/UDP     5800    192.168.1.68    5800

What else do I need to do to get this to work?