Video stops and Chromecast has "unexpected lapse in attention"
Watching Harry Potter and The Sorcerer's Stone today with my wife, the video froze, and after a few seconds, my Chromecast (CC Ultra, fw v 1.24.88223) displayed a message talking about an "unexpected lapse in attention". I had her restart the movie (she was unable to resume and had to manually seek to the place the movie stopped) and it played back fine since. Can anyone suggest why this might be happening and what I can do to prevent it?
Plex server v 3.2.1, Plex for Android v 126.96.36.1993 on a Samsung Galaxy S7 SM-G930T, Android 7.0 build number NRD90M.G930TUVS4BQE1
"Plex Media Server.log" attached.