Okay but have you attempted to use Kodi as your client on Linux? With the Plex plugin.
I’m on a reddit thread discussing what you speak you lack and they are stating it works
To literally quote the thread
“The Plex add on within Kodi DirectPlays anything I throw it. Give it a try”
I can guranatee you it does not work at least not with h265 transcodes. It does work with h265 transcode that is under 1gb. DVD transcoded to h265 works fine. blu ray transcoded to h265 does not work.
I have spent hours trying to figure this out. Everytime I end up nowhere and quit linux. This time I am making an active effort to stay on with it. That is actually an untranscoded video file. i.e. h264.
Please be more clear when you say “it”
Are you saying you tried the Plex add-on on kodi and it didn’t work? Ended up transcoding?
Or are you saying the browser like firefox didn’t work
Direct Play, which is what this conversation has been about.
And are you attempting directplay in the browser or in kodi?
You haven’t answered this question.
I have not tried kodi. Only browser. I will look into kodi after work. I start work in an hour.
when I disable video stream transcoding.
I get this error with anything played anywhere.
Maybe it is an server issue?
Yeah give it a go. People are saying all but HDR10 content works for directplay in it. HDR is pretty pointless though and unimpressive as a person who had legitimately compared it. Resolution is more impressive still. I hope this changes
No current browser supports h265 direct play. I remember reading that chrome is beginning support for it but Firefox has no intention yet
I also know for a fact I made direct play work in vlc. It wasn’t painless though
I think I may be getting somewhere. PlayONLinux is installing the windows 10 version of plex app. I will get back to you if it works.
You can disable transcoding? Thats always a potential solution
I turned off transcoding in jellyfin
I have video stream transcoding off.
How many people are watching?
2 to 3 at a time.
It could be that its a server side issue if the NAS has a weak CPU
Admittedly I disabled transcoding but I did so knowing that was a dumb move. Its caused me more issues than its fixed. I might end up turning it back on BUT is direct play and not live trans-coding a stream that important to you?
Just because the server transcodes doesnt mean it automatically converts it back to h264 and store its on disk. Often its a live stream transcode where it uses the h265 as a source and h264 as the stream output.
As I said prior the lack of direct play seems to be an issue but I dont see it being a deal breaker unless the NAS is too weak to live transcode?
It might help more than just me if you posted the specs of the NAS and the clients playing.
Plex is a difficult media server to work with at times. Sometimes it will have directplay capable clients and still choose to transcode.
3900x shouldn’t be too weak. But it is also my minecraft server cpu/system. Anyways I gotta dip.
3900x, 128gb of ram, gtx 1070.
I tried kodi, and wine with plex. Couldn’t get logged in with wine and kodi kept timing out. For now I am going to run my backup laptop as my htpc for this and use barrier to control it.
New issue I found today. The monitor’s display setting keeps getting reset at random. (waking from being turned off).
Update - Going solid. I installed windows to compare minecraft ray tracing performance. I actually get like 20 fps average better in highs and lows than i do in windows. Can’t seem to figure out why…
This is pure speculation from my part, but, since the Linux driver is Open Source, and AMD have made the long and arduous transition to Mesa, this is not that surprising. The Mesa graphics stack is much more involved than the Windows graphics stack and graphics driver. Here is how Nvidia vs AMD implements their drivers in Linux:
+--------+ +--------+
| Screen | | Screen |
+--------+ +--------+
| | | |
| Mesa | | |
| | | Driver |
+--------+ | |
| Driver | | |
+--------+ +--------+
| Kernel | | Kernel |
+--------+ +--------+
| GPU | | GPU |
+--------+ +--------+
AMD Stack Nvidia Stack
Nvidia implements the Linux drivers just like they do on Windows, but the thing is that Mesa has gotten a lot of optimizations over the years. Since AMD only need to write a small driver instead of a whole reimplementation of Mesa, like Nvidia does, that gives a whole lot of optimization for free.
For sure, AMD still helps Mesa and contributes heavily to it just like Intel does - after all, a really great functioning open graphics stack is in both their interests, no need to reinvent the wheel etc. It is quite amazing what the open stack can do these days. But those optimizations do not usually make it to the Windows driver, which needs to implement their own rendering blob and stuff like that, which is why the Linux version is starting to go faster on some aspects.
Fun times ahead, for sure. Heck; Nvidia is even starting to lose feature-wise to mesa, for real this time. 
I have a challenge for all you Pop OS (and other) users out there. Try getting Pulse Audio to chose 48Khz as the default system sample rate.
Maybe the Plex Web user interface can be a substitute?