AirPlay works for low single digit minutes then drops.
Completely resolved. After tying everything from turning mirroring off to trying every device - 2 iphones and 2 ipads - with no resolution, hard wiring the ATV to my Netgear router solved the problem. Makes sense that since no device would work it must be something common to all devices. You shouldn't have to do that from ATV but I chalk it up to apples proprietary arrogance - AirPlay and ATV don't like going through a non-Apple wireless router. I know that sounds silly by that's the kind of stuff Apple does which is why I have resisted EVERYTHING apple until about 18 months ago. I prefer an industry standard that all can use, not their proprietary BS. (Dont bash me - that distracts from the technical forum).
However it's still mysterious because even though my A/V receiver is similarly hard wired to the router, AirPlay wold not work through my receiver's AirPlay function. ***? I have no answer for this..