Not sure. There’s a few things I’d look at in Plex settings if it was in front of me, but it’s a bit hard to give directions to them here. I’ll give it a shot though:
Make sure that your network isn’t misconfigured so that your client appears “remote” to the server. If your IP address is in a different range (192.168.1.XX vs 192.168.0.XXX for example), Plex may feel that the connection is outside the home, and apply “remote access” restrictions. All clients - by default - self-restrict themselves to 2MBps connection speeds (for some reason). If you do not change this setting up to “Original Quality”, Plex may attempt to transcode to make the video stream fit within 2MBps, which is tiny.
Hmm, for now, without seeing the logs, I cannot think of what else to check. When a transcode happens, there is a line where the server explains why it did a transcode. I can’t recall right now what line to look for specifically, but it is in there. This would be a HUGE clue on where to start to look for this.
I did a quick search, and while I didn’t see the original Plex forum post on how to avoid 4K transcoding, here is an older one on reddit that may have some hints.
https://www.reddit.com/r/PleX/comments/7d5mrq/plex_4k_direct_play_guide/
I don’t know if this is the original Plex forum post I recall seeing, but it is another such guide to look at. It’s only 4 years old, and even IT admits that the information may no longer be relevant due to changes in Plex since then, but might be worth browsing:
I understand how frustrating this all is. Especially if Kodi “just works” out of the box, why doesn’t Plex as well? I don’t have an answer for you. I thought that - on Shield or AppleTV at least - the two clients ought to be closely equivalent in features. But then, Kodi is open-source, openly contributed, and ruggedly built to work against pretty much anything. Plex has more corporate concerns, so some care might be required in keeping certain media decoders out of clients to maintain legal accommodations for Google Play and iTunes stores.
Personally, I used to love Kodi, but I wasn’t (at the time) able to understand the complexities of configuring it to work with my media library. Since then, I gave Plex a try, mangled my library to fit Plex (and now Kodi’s) standards, and could probably swap back. But the power of having a single-server to maintain all metadata is far superior to customizing the same on every single device in my household and on the go.
