Well local ISP's don't block so that's fine. I also use D-Link but with my model I'm forced to manually port forward. What models of D-Link do you have? Your D-Link devices will most likely be the problem! Either set them for UPnP (may require device firmware upgrade), or manually port forward. Opening ports is something you'd also need to do if you were using advanced net games & video conferencing which require a great many ports opened, not just one.

Do this simple test for us. Using your browser go here: http://www3.limewire.com:6346/ The page should say 'Your test worked!'. What happens when you go there?