After releasing the Android version of my app, I went over to iOS mode. I was unable to play any streams until I set the undocumented waitForBuffer parameter to true in TrackPlayer.setupPlayer:

  const buffer = 0.5;
  await TrackPlayer.setupPlayer({
    playBuffer: buffer,
    minBuffer: buffer * 2,
    maxBuffer: buffer * 2,
    waitForBuffer: true
  });

If I do not set this parameter, the stream plays almost directly and then stops again.