Server Version#: Version 1.25.3.5409
Player Version#: 7.27
I used to watch 4k HDR on my iPhone with no issues but a few months ago this stopped working. The video starts but the phone gets hot and, I guess, thermal throttling, the video starts stuttering and eventually I see a slideshow. Can reproduce on iPhones starting from 6 to 12. Switching to the old player in settings fixes this and the video plays with no issues.
Sounds like the Plex app on your iPhone tries playing a video that it’s technically capable to play but as you said brings it to its knees. The same video will probably be transcoded by your server for the old player (and might have been transcoded in the past).
Are you able to play it using a lower quality setting (w/ the current player)?
The old player plays the original quality with no issues and the phone is barely warm. Plex says it uses Direct Stream. With the new player, it uses Direct Play, overheats my phone, and starts throttling. Just tried transcoding to lower quality (40Mbps) and the new player also worked.
But I just don’t see what’s the point. With the new player, I’m losing the HDR content and have to transcode creating unnecessary load to my NAS while the old player just worked.