I’ve had trouble streaming Plex in the bedroom, 4K content only. Lot’s of buffering/stutters.
I still haven’t got around to networking the bedroom to Ethernet, just WiFi.
Out of curiosity I opened VLC on the bedroom Nvidia Shield, and there’s an option to access devices on the local network, including my NAS. Opened the file directly and it only buffered once, slowed for about a minute (the audio sounded like my cat playing with my turntable lol) but then it caught up in 30 sec or so and streamed flawlessly after.
Not sure why it worked better, but figured I’d post here as a hack for others in similar situations.
Not sure how your plex server is set up, but if it’s trying to transcode the content, that could be introducing lag. Some settings to try:
Other than this, try posting over at the forums on the Plex website if you don’t get an answer here.