Actually most of the Linksys modems/routers use UPnP (except for the older models.)

The most important step in forwarding a port is the 1st step; setting up a static ip. It sounds like you did it incorrectly which is why it only worked temporarily until your ip address changed. I'd suggest you cancel your forwarding & redo it.

Go to http://www.portforward.com/routers.htm

Also see http://linksys.custhelp.com/cgi-bin/...TVUxMA**&p_li=

& also http://linksys.custhelp.com/cgi-bin/...type=search_nl