The problem 'might' be your router. Routers generally use NAT for protection of incoming messages. It has a similar effect as a firewall though it is not a firewall per se. Many routers nowadays have UPnP which allows a program with UPnP abilities such as LW to communicate with the router directly to request a port be opened for that session. However, sometimes the implementation of UPnP is not good, or other reasons UPnP communication is being broken. So in those cased, manual forwarding (opening) of a port is best action.

1. To do this, the very first thing you must do & most important step is setting up a static ip, without this done first, the process will not work. Instructions setting up a Static ip on Vista

2. Then follow directions here: Port Forwarding for the Vonage VDV21-VD Keep in mind for 'some' brands of routers, you need to either or both reboot the router to fully save the settings & get them into action, else reboot the computer after doing the above processes.