Wow, that's a pretty extreme fix, and it should not be necessary, but I'm glad it solved your problem. I am having a similar but different problem. I use AirPlay from iPad to Apple TV for Amazon Video. Before I upgraded to iOS 11, it worked very well. Now, the connection drops after 2:50 (2 minutes, 50 seconds) of streaming. The connection persists when I am only screen mirroring. But as soon as I start streaming in the mode where video appears only on the TV, a timer starts somewhere and it's going to drop 2:50 later. I've tried a lot of the usual suspects. The problem is consistent. It's hard not to blame iOS 11.