I actually got mine to restart the next day, and I’m not even sure what worked. The things I did the night before didn’t work. The following day,, the episode suddenly played. And I have had no trouble since, which is even stranger because I anticipated problems!
The things I attempted were all the normal things you would think to do. Powering the cable box and the modem on and off. Unplugging things and plugging them back in. Removing AppleTV from my Samsung TV and reinstalling. Trying it on my iPhone (worked). None of those things worked. But the next day, all of a sudden it began working again.
I wish I was more helpful!