Apple TV 3rd gen (A1469) Air Play suddenly stopped working

I'm trying to AirPlay from an app on my iPad that always worked before...it allows me to stream TV programs from overseas. I've also tried to make it work from my iPhone to see if the iPad is the problem and it's not working from it either. I was able to make it work the day before and for about two yrs before that. I've checked everything and I don't know what went wrong all of a sudden. Nothing appears to have changed in the app either, but I've contacted support for it and I'm still waiting to hear back from them.

I'm completely baffled. No problem with Prime or anything else. In fact, I've never had an issue with it before.

I didn't even think to try AirPlay with a different app because I've only ever used it with the one. I just tried it with You Tube and it worked (I should have thought of that). I'm only ever given two AirPlay receiving devices to choose from, the Apple TV and the device the app is on and I always choose the Apple TV.

As stated in my previous reply, I already contacted the app developer the first day of the problem and I'm still awaiting their response. So I know now that the problem is most likely with them...makes sense.

Thank you for helping me narrow it down.