HELP! Plex Transcoding is unreliable

Desktop Build:

MOBO: AB350-Gaming3
CPU: AMD Ryzen 5 1600 (3.2Ghz, 6 Cores)
SSD: Samsung 850 PRO (512GB)
RAM: DDR4 32GB @ 3000Mhz
Page File Space: 2.38GB
VIDEO CARD: NVIDIA GTX 1060 3GB
OS: Win 10 Pro
Remote Access: Fully accessible outside your network

PLEX Storage:
D:\ 8TB EXT USB HDD (7200rpm) WD (Probably White Label)
G:\ 8TB EXT USB HDD (7200rpm) Seagate
H:\ 8TB EXT USB HDD (7200rpm) WD (Probably White Label)

Home LAN: 1Gigabit
Modem/ISP: 400Mbp/s D / 40Mbp/s U

Plex Transcoder Settings:
Quality: Automatic (I’ve tried all 4 settings, and it has not stopped issue)
Transcoder temporary directory: (Blank)
Default Throttle Buffer: 60 (I’ve bumped this up to as high as 600 and as low as 60, issue remains)
[X] Use Hardware Acceleration When Available
[X] Use hardware-accelerated video encoding
Maximum Simultaneous video transcode: Unlimited

1080p MKV Container w/ Subtitles (1 stream only)
–Takes CPU up to 25% Usage
–GPU up to 15% Usage

Media Clients: PS4, Xbox One, Tablets, and PC.

I experience a lot of buffering/and a lot of issues when it comes to MKV files with English Subtitles. Often with Anime I end up having to back out of a stream, re-enter, backout, re-enter several times in order for it to finally work for a Japanese Audio/English Subtitle 720p or 1080p MKV container. I have 8TB of Anime, all from different sources, and this behavior is prone to all of them. Same goes for Chinese or Bollywood Movies that have English Subtitles. These are not using external .srt files, but rather ripped into the MKV container. Streams do work better on the PC than the Xbox One or the PS4, but I am not sure why that would be the case if the ‘server’ is the one doing the transcoding.

So my main question would be… Why is this happening? Where is the bottleneck? Or if it’s a setting, what would I change it to?

Is it from using External USB HDDs?
Is it just the CPU or GPU is too old or maybe not compatable with Plex Transcoding?
Is my page file too small?
Do I not have enough RAM? Is the RAM too slow?

I have been considering going all out on a dedicated PLEX Server, but my knowledge is limited atm and the more I google, the more I see conflicting opinions on “best builds”. I see people with these DIY budget builds that transcode @ 4k and I wonder why I have such issues with 720p and 1080p files.

You may have a router issue. Have you did any port forwarding? UPnP turned on?

Are you running Ethernet to the router from your plex server?

If they are transcoding 4k, it looks terrible. 4k is direct play only.
Don’t believe stories about how t̶h̶e̶i̶r̶ ̶u̶l̶t̶r̶a̶ ̶i̶n̶e̶x̶p̶e̶n̶s̶i̶v̶e̶ ̶b̶u̶d̶g̶e̶t̶ any build transcodes 4k.

My current set-up is:

Modem -> TP-Link AC2600 WIFI Router -> 6-Port 1Gigabit Switch.

Off of the Switch is the Plex Server, PS4, Xbox One, Other PC, etc.

UPnP is also enabled. My NAT Forwarding is set up for PLEX (Port 32400 TCP/UDP). No VPN is configured. SPI Firewall is not enabled on Router.

There’s no reason to use UPnP and port forwarding. You should only port forward the necessary port, disable UPnP entirely.

Ok…you do have a Plex Pass Subscription?

I’m spit-balling but make sure DLNA is enabled

My issue when I got started had to do with DNS Resolving but I’m using PfSense. Once I got that sorted out I had a green lock icon and everything worked pretty good…then I got Plex Pass and worked great.

Yep, have a Lifetime Plex Pass and DLNA is enabled. I don’t know if it’s the slower USB 2.0 speeds that my External HDDs connect to on this box (as there aren’t enough USB 3.0 ports to go around on the case I have). Also these External HDDs go into idle when not being accessed, which I would assume would cause initial lag but then work perfectly fine.

I think it might be time though to figure out a solution (standalone Plex Tower w/ internal SAS drives) and then maybe think about upgrading LAN to 10Gbps.

Personally I don’t see a huge issue with your current setup other than I have no PMS experience on Windows. The usb 2.0 thing could be causing the issue but I kinda doubt it. I’ve used an ext hdd on a Linux setup with no issue. Obviously you’ll see better results with sata, sas, or nvme attached storage media. Also you would do better to have a modern Intel processor with QuickSync. You don’t have to get carried away here…there are a few threads on the subject in this forum.

I know subtitles and transcoding can be an issue but I’m not well versed enough to talk intelligent about it. If memory serves it has something to with the video encoding…maybe specifically VC1. Perhaps a lot of your anime is in VC1.