Unable to use AirPlay with TV app
I've been trying to watch a TV series with the TV app and AirPlay. I have an old Apple TV device which won't let me sign in any more (probably related to 2FA) but does show up as an AirPlay device on the network, and otherwise seems functional.
If I attempt to send a show that plays on my phone (the screen is too small to watch it on, though) to the Apple TV I see "there's a problem loading this content".
Can anyone suggest why that might be so?
iPhone 8, iOS 13