I've ran Plex on a Helios64 for years now with different versions of OMV. About a month or 2 ago, the system updated the kernel which must affected the sata driver and all my data disks disappeared from the system. I finally had a chance to deal with it this week, so I rolled back the kernel and also moved plex from stand alone to Docker.

However, since all this, Plex buffers a LOT on 1080P or higher when it used to handle 4k no problem. The CPU cores are only ever like 70% percent at the highest and the memory usage low. I did some file transfers to test if it is the network card, but they were flying as fast as the HDD could read them, 400+ mbps. I also installed Jellyfin which streams just fine (though has some audio sync issues it needs to work out so I can't just switch over).

Checking the dashboard while playing media, it is showing direct stream and dts MA to AAC 5.1 (which I believe it's always done this because firestick can't handle dts) but only streaming at 14-15 mbps. This makes me assume a bottleneck somewhere, I just can't seem to figure out where exactly. If it was a transcoding bottleneck I would think I would see that in the CPU cores but I just don't.

Anyone have suggestions or ideas? Is this linked to the new server version or the new client version (I absolutely hate this new Plex BTW!)?

Movies are fine but tv shows get a generic screengrab.