Q: Apple TV update 7.03 brakes Airplay from IOS 8 device

I'm having an issue with my AppleTV's not even showing up on any iOS device's AirPlay menu. The iOS device and the AppleTV/s are on the same network, the network is functioning and I can see that the AppleTV's are present on the network. But no matter what I do, I can't get the AppleTV to show up as being selectable for AirPlay. This problem has only started after I upgraded to 7.0.2. I was hoping 7.0.3 did something to resolve this but the issue remains the same. This has made all of my AppleTV's running 7.0.2 and above un-usable.

Meanwhile, my older 2nd gen AppleTV's running 6.1.2 are still working perfectly. What can I do about this? I've factory restored the device/s many times to no avail. I have (of course) restarted the AppleTV's and have also tried using ethernet but that doesn't work either. Unfortunately most of my classrooms using AppleTV don't have ethernet connections available so we have to rely on the WIFI.

What other solution is there? No network changes have been made that could specifically relate to this to my knowledge - and again, AppleTV's running 6.1.2 work fine. Unless something has changed on the networking side of the coin with the 7.X.X firmware? I can't find a changelog that specifically addresses what bugs are fixed (if any) or changes made. Desperate for a solution here.

Addendum - found the changelog but it doesn't appear to reference any of the issues I'm having specifically.