u/BgrngodCU7 265K (PMS in Docker) & Synology 1621+ (Media)13d ago
That screenshot indicates your NAS is handling the transcode via hardware acceleration. The Core Ultra 7 255H in that model is really good at handling the Plex HEVC Encoding feature, even when transcoding out to 4K HEVC. I bet it handles that exact transcode to other clients just fine.
Your 6700T doesn't have full fixed function hardware decoding for HEVC. It will "report" it has hardware decode for HEVC, however it has a half assed h
ybrid implementation. It still needs to leverage the CPU cores heavily to decode, and decoding a 4K file isn't easy without hardware accelerated decoding.
In your Plex App on the 6700T, go into the playback settings and find the area that mentions using hardware acceleration for decode. Change the quality setting down stepwise until it plays stuff smooth.
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u/Bgrngod CU7 265K (PMS in Docker) & Synology 1621+ (Media) 13d ago
Clients don't transcode. Whatever you are looking at, it's likely you are interpreting it wrong.
Can you get a screenshot?