UNRAID Plex Server Stuttering

[Melfox01]

While streaming, even on my home network, video files frequently begin to stutter like the file needs to buffer and I am not (yet) technically literate enough to figure out why. Doesn't always happen. Such as I'll be halfway through a DVD quality file and it'll just start stuttering for a while. I imagine there's some part of the chain that needs to be updated, but I'm curious if someone can tell me what is most likely to be causing this. HDD vs SDD? Drives too full? Router speeds? Ethernet card? CPU? Cache drives? Client end? Just not sure. As to the specs, probably very unbalanced. Had some other ideas when I initially built the server.

 

Specs
Motherboard: MSI Z370 A-Pro

CPU-i5-8400 (thought it should be able to transcode 6 concurrent streams)

RAM: 16GB DDR4. Can't remember the speeds, nothing fancy

Drives: 6x4GB WD Red.

Arrangement: Unraid Single Parity.

Drive use: Parity drive: 3.01/4GB full, Plex drives: 1.24-2.71/4GB full (originally set to stop at 1/2 full then move to the next one, but added an extra drive to that Share). Disc 4 is a file server share.

Cache Drives and GPU: None

Add ins: Gigabit network card with 2 ports. eth2 is the active port.

Clients: iPhone, iPad, MacBook Pro.

 

I understand off my local network the 20-25Mb/s Upload speed from Comcast is the limiting factor, but I figured I should be able to stream multiple BluRay original quality streams on my network. Am I making an incorrect assumption/calculation somewhere and do I need to upgrade/reconfigure something?

 

I appreciate any assistance that can be provided.

[jj9987]

Are you transcoding or using DirectPlay? What kind of content are you watching (resolution, bitrate, HDR yes/no)?

[Melfox01]

The source files are all .mkv so I'm going to say Transcoding. But sometimes I'll get the same performance while playing the .mkv files directly in VLC. Resolution ranges from 720p to 1080p. Bitrates between 2000-34000kb/s. Pretty much just DVD and Blu Ray rips in .mkv format ripped by MakeMKV. While artifacting and stuttering are more common at the higher bitrates, I have seen it happen on 720p files as well. No HDR.

[Melfox01]

To confirm, just tried playing a 34Mb/s file through Plex and got artifacting even though Plex shows the buffering out in front of the current play position. When I placed the same .mkv files directly in VLC it was clean until I skipped ahead. Then it stuttered significantly (played for a few seconds then paused for a few seconds. Rise and repeat). 34Mb/s should be well within local wifi capability (service rated at 200Mb/s and using the last generation AirPort Extreme before they were discontinued as a router, so it's not super old at least).