i had the same prob with my d-link 604.. i think that was the model..
anyway go to your router seutp page.. for me its
http://192.168.0.1 and enter your pass.. and i think you have to go to misc items.. then enable "IP address of DMZ host" then go to ipconfig and find the last 3 numbers.. put those in and click save.. that fixed it for me.. i know its confusing but gl anyway :/