Is your D-Link actually set up for UPnP or even have the capacity. My D-Link model doesn't support it. I had to port forward it instead.

Otherwise, go to Tools>Options>Advanced>Firewalls & change to port forward & choose a port number between 49152 - 65535. Else leave it at UPnP but change only the listening port so it doesn't affect your Netgear's UPnP communication.