What is the bottleneck in this situation (Plex server / drives / network)

Figured I would ask this here, as I was wondering whether a 10gb network upgrade would be worth it.

I have 14tb 7200 RPM drives, running on a Freenas server, and I have noticed some bottlenecking when trying to use Plex, for example. I have tinkered with Plex til I had a headache and I don’t think the bottleneck is that - I have also noticed it is incredibly slow when moving data around from one place to another.

So my question is, should I be upgrading to a 10gb internal ethernet system or should I be upgrading to some sort of cache system in the server to assist the drives?

If either of these are actually an answer - and they may not be - could you point to some resources to assist me in getting either/or/both of them done?

What issues do you have with PLEX?

I don’t think NIC speed is your issue unless the link is maxed out from other traffic already

1 Like

My problem with plex is issues while playing UHD movies when streamed over an internal lan to my TV, with 20+ gig file size and the fact that it will buffer on me just pause - I can lower the rate on it but that also lowers the image quality.

I have internal ethernet over power which is rated for 2.5gb, I have set up direct play, and tinkered with the settings - but I can’t get it to consistently play without buffering. The TV is a Samsung OLED and I don’t think that is the problem.

It has settings for 20mbps and I have tried them all down to 4mbps to try and get around it, but once you go below a certain level the image quality suffers quite a lot - which negates the point of the file size.

I thought it might be the network as the drives should be good 120 MB/s at 7,200rpm.

I am however not an expert in Plex, so I was kind of guessing that either the drives are not fast enough or the network is limited.

I put $10 on the TV, next suspect would be ethernet over power

Have you verified its direct playing?

Can you temporarily run ethernet directly to it to rule out the ethernet over power?

My NVIDIA Shield would struggle with a lot of UDH movies. Ditched that junk in the end and went with Apple TV. Android TV is just completely trash IMO


Is the file getting transcoded? Your hardware might not be fast enough to transcode 4K, especially HDR.


I don’t think it is ethernet over power, I use it throughout the house, including in my office and I get my “full” UK download speed of 34 megabits per second (wooo) - no problem.

I just went and tinkered some more with some more settings - and it appears to be working again, sorry for the pointless post but working through this forced me to go find more information that I had on hand - and I don’t think there is a bottleneck at all.

I think I may just have had it set up incorrectly. Running a 60gb file right now no issues.

1 Like

That I am not sure about, it is an old i7-7700k so doesn’t have the newest transcoding stuff on it, but I found another setting in Plex that I had not seen before.

I had set the transfer rate to 20mbps - but then when going through the menus, I found another menu that set the transfer rate - which was set much lower - so I set that to 20mbps as well. Once I had done that I had no issues.

I wonder whether there was a conflict between the two settings, as I played both 25gb and 60gb files after that and both worked without any issues at all.

1 Like

Would you mind sharing what settings you changed, for the benefit of those who will find this thread through search in 2 years’ time, pulling out their hair with the same issue? :smiley:

1 Like

As soon as you start messing with limiting transfer rates you involve your Plex server transcoding.

Turn that off and see if it works. If it does with the bandwidth limit turned off then you’re probably looking at a transcoding issue.


everything everyone said here is right on point so glad to hear you played around with the settings and found a fix for your issue. I like playing around with settings too, troubleshooting is fun for me because its like solving a puzzle! Will also add that another testing thing we’ve done is allow insecure sources… this is no issue if you’re on a home plex thingy and just want to test every possible thing that could be causing an issue but yeah flaky streaming and buffering from powerline adapters is basically a given if you have a old house but forcing transcoding when direct play is the best choice will deff buffer you up.

Also sometimes the settings aren’t always sticky, so you might need to not just go into the main settings and set play original file/direct play/ whatevz but when you open a file, tap the three dots and make sure that its set to play original quality.

Also sometimes adding subtitles mid-play can cause issues too, others here on level1 have talked about how adding subtitles have forced a transcode instead of just adding text like it should.

Since the sort of content you want to watch isn’t your average 1080p stream, and i really doubt you have a 1080p tv since 4k is so ubiqitus everywhere, on the off chance u do have a 1080p tv, one of the biggest bottlenecks i have found is accidently setting a stream which is already 1080p to transcode to 1080p, so like for like just lesser. Plex really gets irky about this… but yeah probably does not apply to you but just one of the things i learned breaking plex for fun :smiley:

edit: oh and just quickly, one big streaming quirk i have found is for files that have audio setups beyond my tv’s ability, so like the super fancy surround 7.1 stuff and all that… forcing to default to two channel or the 5.1 one has fixed a whole bunch of streaming issues too…

Happy streaming!! :partying_face:


It sounds like you’re talking about the general stream limit and the person/user limit settings. It’s been a while since I used Plex but I think the general or network setting limit is only applied to remote computers as it’s designed to allow you to get more streams on limited bandwidth connections.

What you should check is on the client side bring up the stats for nerds and look to see what mode it’s playing in and what the bitrate is.

You should strive to make sure everything playing on-LAN (in house) can direct play. That means having a stereo audio channel available as well as any 5.1,7.1 types so you always have an audio stream that can play without requiring a transcode. You will want to test all clients to make sure they can direct play your highest bitrate non HDR files without pauses or stutters. Typically it’s non Ethernet connections that have problem such as WIFI, EOP & MOCA. WIFI can work great one test and fail another time when other devices are actively using WIFI.

Older MOCA typically have lower connect speeds and can struggle on high bit rate files. Multiple clients on the same MOCA ring all contend for the same bandwidth. 2.5GB MOCA will normally deliver something similar to 1GB Ethernet speeds and work ok.

EOP are hit and miss depending on distance, quality of electrical wire, other things running on the same phase and of course the speed you connect. Electrical motors can give EOP fits.

In First glance seems caching/ram issue.