Here are the instructions for forwarding a port for the
linksys model WRT54GV2 & you should choose port no. 6346. You'll also need to Force IP within LW using the same port number. See
LW settings instructions for Force IP: (& image sample) This should fix your problems. It would be worth doing another incoming test to ensure that everything is OK. Tell us how you go. The only points about your modem are 2 plus & minus reviews:
here & also
here