Micro stutters / single frame drops

[TheDreadPirate]

This would be the CPU/GPU/SoC on the client, not server.

Its extremely hard to find documentation for the SoCs built into Firesticks, Chromecasts, and Rokus, etc., but a lot of them will have a max bit rate they support decoding.

I almost guarantee if you recompressed your remuxes to a lower bit rate this problem goes away. The fact that it plays fine when you lower the "quality" on the client to a lower bit rate, triggering transcoding to that lower bit rate, kind of confirms that.