DLink may not be the most reliable at UPnP, thus, perhaps you should port forward your device. Most important step is step 1 which is setting up a static ip: Setting up Static IP for VISTA (click on link).

Then follow these directions Port Forwarding for the D-Link WBR-1310

In my experience, D-Link requires both saving the settings after changing, then rebooting the router to enable the new settings to come into operation.

Re: Vista firewall, see User Cant Connect - LimeWire

Your ISP is infamous for problems with p2p. It might be worth checking for Optimum issues & suggestions & ports to use here ISP's known to BLOCK or Filter p2p or specifically Limewire (Optimum can be found on the list). So perhaps you should apply such a port for port forwarding, such as port 64049 for example.

Edit: I had a problem similar to yours when I got a D-Link router (could download but rare sharing & I knew downlding could be better.) After port forwarding all problems solved.