Give port forwarding a try this is what x10 has to say:
http://kbase.x10.com/wiki/Port_Forwarding_For_X10_Software"If you are still unable to connect, the issue is most likely due to a firewall or network security configuration (Zone Alarm, Norton Internet Security, Windows XP Firewall, Router, McAfee Personal Firewall, etc).
The ports for X10 are 8080 and 8888 (TCP).
You may test the above ports for connection status with our Online Internet Connection Test on the following page:
http://www.x10.com/support/netinfo/netinfoadvance.htm Make sure to Show Advanced View and put in each port number specifically and individually in the Listening Port field at the bottom.
If one or both of these tests fail, it may be because a firewall or router is blocking or rerouting ports on your computer. Try disabling any firewalls, or call your ISP or router manufacturer to find out how to open or "forward" ports to your computer.
If you are using a router, it may also be necessary for you to setup a feature called port forwarding inside of your router's configuration. This will ensure that when information is sent through the ports, they are tagged with the proper IP Address for routing. "
