I'm having similar problems with my Denon media clients having recently *up*graded from a Netgear ProSafe router to a 2860n. I can stream music ok, but the Denon iOS app doesn't see the devices automatically and I have to manually enter their IP addresses. Even then, the Denon app can only control basic functions and doesn't see the media server. Everything worked perfectly with the Netgear router (and works again if I switch out the 2860n). I have uPNP enabled and both services enabled.

I see no evidence of any ports being dynamically opened, where can I monitor these?