Technicaly !!clarkkent answered your question correctly BUT...
... I think you're talking about 2 different things.....
Usulay the UPnP in a router is what lets it open and redirect ports to specific computer, like for gaming and such...
UPnP in the DNS-323 is actual a "A/V Server" meaning its used to server (stream) audio and video
So both are different.... and yes you can have the UPnP AV Server on the DNS-323 at "on" while UPnP on the router is at "off",