Fire TV stick - adjusting stream quality for low bandwidth connection

Server Version#: 1.19.1.2621
Player Version#: Unknown, but setup a week ago so whatever the latest Fire TV app is

A friend of mine is using a Fire TV stick to stream SD and HD content from my media server. SD plays fine, HD stutters a lot which suggests to me that bandwidth may be an issue? I have 50mbps fibre on my end and I suspect they have 2mbps at theirs. Is there a setting on either the media server or fire TV stick side that can downscale or maybe buffer the content so it does not stutter? In essence, they would rather watch smoother SD content than stuttery HD. Ideally I want a solution that only alters their experience and not for the rest of my family who don’t have this problem.

Apologies if I am using the incorrect terminology.

Adjust Remote Quality in the Plex App - at the slow Remote Connection - to 75% of THEIR DOWNLOAD BANDWIDTH… NOT YOUR UPLOAD BANDWIDTH. <—you need to find out what that is - so you can have them adjust to it.

Then turn on Automatically Adjust - if available - on that Remote Client. <— the stream must start in transcode, but when it does, it’ll adjust itself to the conditions.

That’s all you can do.

I had a friend with really crappy internet. Really Crappy.
I had him set Remote Quality in his FireTV Plex app to 1Mbps - we got as close as we could to just keep it in HD… barely.

That got all the streams transcoding and they would adjust down (making Live Moon Walk Footage seem great), if necessary, but at least it kept playing - and it got pretty bad at times… bad enough my friend called CrapCast and dumped whoever he had - he was paying for internet he couldn’t use.

It’s all better now - I had him open his Remote Quality wide open to Original and Disabled Adjust Automatically as it was no longer needed - and I’ll fine tune it the next time I visit.