Plex 4k buffering

Hi,

I'm looking for some help to solve my 4k streaming problems with Plex. I'm certain I have streamed them before in exactly the way I'm trying to now, but now it isn't working and keeps buffering all the time.

I can provide logs etc if needed but to me they don't say a whole lot. The computer I host my plex server on is nothing special and has a i5 8400T processor but the files i'm playing are not being transcoded so I don't think that matters.

When I'm playing one of the files which is HEVC 10, 80mbps bitrate I can see on the plex dashboard that it is using around 100mbps to send the stream onto my network, my router then says that this computers is only using around 10mbps.

The files are stored on a DLink 320L, which honestly is a bit of an older NAS drive, but it has Gigabit Ethernet and the CPU usage sits around 20% and the RAM is around 90% but it always is.

My router is an Asus RT-AX92U, the nas and plex server are both wired into one AX92U then I have another under my TV which is an LG 65C9PLA OLED with plex app installed. Everything is cabled with at least Cat5e.

I'm convinced its a Plex issue because I can play the files perfectly through VLC but if anyone can suggest anything I can try to get this working that would be great. Its also worth noting that I have some 4k videos that are 20mbps and other that are 50mbps and 80mbps, the higher the bitrate the more if buffers obviously but some of the 20mbps ones I have don't buffer at all. all files are mkv and I get the issues on every device I use to playback, desktop, phone, TV's.
 

vtec123

Member
Have you rebooted everything ..? can you monitor the traffic from plex server to T.V to see how much bitrate it is being received?
also have you got subs turned on that will cause buffering ?
 
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I have rebooted everything yes, subs are turned off server side and I'm not sure how I directly monitor those 2 things, there isn't a function like that on my router but I have attached a screenshot from the router and of plex network stats. That shows the whole internal load of my network and plex playing a file on my computer.

Screenshot 2022-01-11 205616.png
Capture.PNG
 

vtec123

Member
Is everything from server to T.V connected via ethernet..? If yes is it Gigabit Ethernet or 10/100..? If its Wi-Fi 2.4 ghz will not stream some 4k files due to file size over network..5ghz will.
 

vtec123

Member
Can you post the following info below like I have..
As you can see my 4k file going to my t.v is 83 Mbps..some time the files are 168Mbps.
 

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outoftheknow

Moderator
I have rebooted everything yes, subs are turned off server side and I'm not sure how I directly monitor those 2 things, there isn't a function like that on my router but I have attached a screenshot from the router and of plex network stats. That shows the whole internal load of my network and plex playing a file on my computer.

View attachment 1634689View attachment 1634688
The bandwidth is dropping too low to support streaming 4K - or close to it depending what bandwidth Plex/the app behind it uses to deliver 4K.

4K needs "25mb/s" to stream. Netflix won't deliver it if available bandwidth is under that (at least it says that is a criteria for delivery). Some will deliver it around 15-20mb/s but that is a little "light" (on purpose to reduce the number of people complaining about the service "not working").

Those dips to less than 31mb/s will almost certainly be the issue. the buffer won't be big enough for the time shown there for those - although scales are hard to work out of course.

So when you say through Plex does the same app accessed directly deliver 4K smoothly? Are you using a VPN with Plex/apps to access paid for but geo-locked content? Is the content on a CDN server in your country so the dips are a local connection issue? Are kids streaming at the same time or otherwise others are using connection bandwidth? Can you apply some QoS settings at the router for your use with Plex?
If its Wi-Fi 2.4 ghz will not stream some 4k files due to file size over network.
In theory that shouldn't be true. The size of the file isn't relevant as long as the bandwidth available for the stream is more than the stream requires. 4K needs 25mb/s bandwidth to stream. Likely the stream is nearer 20-22mb/s and the rest is overheads allowance. With bandwidth always above 30mb/s and a stable connection the stream will be smooth without even eating into the buffer.

Even ancient g wifi was a maximum of 56mb/s and with a decent connection and capable router that would be enough (as a single stream). N was up to 300mb/s years ago and some routers now offer up to 600mb/s on 2.4Ghz. 5Ghz will offer a faster "link speed" but that isn't what s required. a "slow" 72-144mb/s 2.4Ghz link is fine - the connection stability to deliver over 25-30mb/s is the first critical issue I would suggest.
 
I think the issue is solved with a firmware update of my routers, I have tried the same files over the weekend and they now play without buffering as I expected them to. I have a mesh wifi network and one of my nodes was on a different firmware to the other and they wouldn't update so I flashed them manually and now it looks good.
 

oneman

Well-known Member
I think the issue is solved with a firmware update of my routers, I have tried the same files over the weekend and they now play without buffering as I expected them to. I have a mesh wifi network and one of my nodes was on a different firmware to the other and they wouldn't update so I flashed them manually and now it looks good.
I thought you said in your first post that everything is wired ?
 

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