Why are my 4k streams, and even some large 1080P streams buffering through my LAN?

[Old_Rager]

Server Version#: 1.41.0.8994
Player Version#: 5,88.1 (Samsung TV version)

My PC case is able to run two separate MOBO’s - EATX and an ITX. My Plex server is on the ITX MOBO which is an ASUS ROG Strix X670E-I Gaming WIFI with an AMD Ryzen 9 7900X 12 Core AM5 4.7 GHz CPU and 64GB of DDR5-6400 RAM. The GPU that is being used is the inbuilt one that resides on the CPU. The MOBO has a 2.5GbE network port but I am currently using the inbuilt Wi-Fi 6E (2x2 Wi-Fi 6E (802.11 a/b/g/n/ac/ax) that supports 2.4/5/6GHz frequency band).

My main PC is on the EATX MOBO which is an ASUS ROG Crosshair X670E Extreme with an AMD Ryzen AMD 7950X3D CPU and 64GB of DDR5-6400 RAM. The GPU that is uses is a dedicated ASUS Radeon RX 7900 XTX TUF OC. The MOBO has a 10GbE network port but I am currently using the inbuilt Wi-Fi 6E (2x2 Wi-Fi 6E (802.11 a/b/g/n/ac/ax) that supports 2.4/5/6GHz frequency band).

I’m currently waiting on the following switch ( Multi-Gig Switches – 6-Port 10G Switch | TRENDnet - TRENDnet TEG-S762) which will give me 2 x 10GbE and 4 x 2.5GbE ports which I am hoping will fix my issues.

My TV is a Smasung 900C which is an 8K TV which can do 120fps in 8K or 144fps in 4K and connects to my LAN via its WIFI 6E NIC, but it also has 1 GbE port which will also be connected to the switch once I have it. Lastly, the router that I’m using for the LAN is the one that was provided by my ISP and is a TP-Link VX420-G2V which is a dual band router that does 5808Mbps on 5 GHz and a further 574Mbps on the 2.4 GHz spectrum. I also have a fibre to the basement that can theoretically get ~900Mbps down and 110Mbps up speeds, but whilst running everything on over WIFI, I generally get ~550Mbps down and 45Mbprs up speeds.

So basically, when some people access my Plex server from outside, they can stream 4K content reasonably well, but a mate who is running Plex on his PS5 finds that even 1080p content buffers for him. When I run 4K content over the Lan, I generally get buffering issues - and even on some large file sized 1080p, I even get buffering.

Seriously, this is driving me mad. From what I can tell, my Plex server should have the plenty of grunt to transcode anything on the fly, but I get buffering over the LAN
more often than not. Does anyone have any idea what I am doing wrong here in my setup to cause it to buffer so much?

Any help anyone can provide is greatly appreciated.

Dave.

[ChristianKent]

When it’s buffering is it transcoding? Do you know how you can tell when it’s transcoding? Have you done any speed tests from server to client? You can use iperf3 or openspeedtest. You don’t need a transfer rate of 2.5Gbps to watch 4k. That would be ridiculous, lol. The typical bitrate for 4k remuxes is around 100mbps so a gigabit lan would be more than enough.

Also, sometimes, some clients can’t process ultra-high bitrates because of their internal memory buffer limits.

If it’s a Linux server, turn on TCP BBR. If your mate is far away, it will help a lot. If you set up an openpeedtest server, you can rule out your connection. Don’t just assume that if your ISP speed is good and your friend’s ISP is good, the connection between you and him is also good.

You can narrow down the problems with your TV if you try different devices where the TV is plugged in. Also note that some TVs have a 100mbps ethernet port not a gigabit port.

[Old_Rager]

Hey Christian, thank your for your thoughts.

I have run the internet speed test using the site that you recommended and the following are the results both with the VPN and without VPN.

With VPN:

Without VPN:

I have also run the IPERF from the main PC to the Plex server that was set to listen and the following is the result that I got:

So, I guess my question to you is, can you see any reason as to why I am experiencing so much buffering - especially with 4K files. From what I’ve read, a 100Mb connection is supposed to be fine to transmit an 8K file at 120fps, but I struggle to get 4K files to work OK.

I will say that I am really unimpressed with the video card I have and its ability to display colours correctly, let alone any HDR files on the Windows system which is why I try to run it from the Smartapp running on my Samsung TV (and you are right, it only has a 10/100Mbps ethernet port) as it tends to present the best picture. Also, when using Plex on my main system (a client accessing the Plex server over the LAN), the images tend to come across in a jaggered way as opposed to watching it from the Plex app on the TV which renders everything very smooth indeed. In fact, even watching the media as dished up by the Plex server on the actual Plex server itself, again they are also kind of jaggered.

Honestly, I have thrown all sorts of money at this thing and still can’t get an optimal result. I honestly do not know what else to do other than get this switch as well as possibly a WIFI router that has a 10GbE port to connect to the switch as well as running WIFI 7, as at least I will get over the current routers WIFI 6 limitation when everything else is WIFI 6E.

Additionally, how can I tell whether the Plex Server is transcoding or not? I have thought about optimising my media to try and reduce this issue, but I have like 5K+ media on my server as it has 70TB of storage.

Any thoughts you may have here are greatly appreciated.

Dave.

[ChristianKent]

You can look at the dashboard when something is playing and it’ll say if it’s direct playing or transcoding. It’ll say (HW) if it’s using GPU instead of CPU.

So those speedtests are from your friend’s PC connecting to your server? Because that kinda looks like a Comcast upload speed. If it’s your friend’s PC then your upload is good since he’s downloading at 422mbps and 626mbps. But if 45mbps and 39mbps is your upload speed on the server then that’s the reason why remote clients are buffering.

So my suggestion is to read/watch videos regarding buffering since that seems to be the area you’re lacking knowledge on. You seem pretty good with networking already so I doubt that’s the problem. Transcoding is a big reason for buffering since it has to convert/re-encode the video on the fly. There are various reasons why a video won’t direct play, like compatibility of the video or audio codec. Sometimes PGS or ASS subtitles aren’t supported by the client so it has to “burn-in” the subtitles, which means transcoding.

I assume you checked the options to enable hardware transcoding? Your CPU should be fast enough that whether you use CPU or GPU it will perform just about the same. Altho in my experience GPU transcodes faster.

In the plex dashboard, you will see two progress bars, one is orange and the other is dark orange. The orange one is the playhead, the dark orange is the transcoded buffer. If it says that it’s transcoding and you don’t see any dark orange, it means your device (or settings) is not transcoding fast enough. Test it and play an easy low-bitrate file. Make sure you’re transcoding by changing the quality to a lower value like 720p. Then see how fast the dark orange fills up. Now compare that with a high-bitrate file.

That should give you some clues as to what’s going on.

[Old_Rager]

The Openspeedtest result is my PC’s access to the internet. The IPERF3 is between my Plex Server and my main PC on the LAN. I didn’t think that there’s a way for me to test my mates connection which is in Sydney, Australia to where I am in Brisbane Australia - some 1,000 KMs north of him.

Please excuse me, but I am doing the best I can to work things out, but I didn’t think that testing between him and me was possible.

Additionally, yes, I have selected using GPU to do the Transcoding - having said that, because I am not using a dedicated GPU but the GPU that is on the CPU, should I leave this as being checked or should I uncheck it?

I decided to buy this router instead of the switch (at least for the time being):

Archer BE900 — The World's First Quad-Band WiFi 7 Router

I will leave the TV connected to the LAN over WIFI with the two PCs (main and Plex server) hardwired to see if this makes any difference. I have no idea why my 4K files buffer so much over the LAN as well as why the picture using Plex on my main PC’s browser stutters or jaggers so much. It is not smooth and is really disconcerting to watch…

[ChristianKent]

When you setup an openspeedtest server (I think you’re just doing the speedtest and not actually setting up a server), your friend will go to your server at HTTP://[your IP]:3000 and it will load up a your speedtest server, that’s how he’ll see what his speed is to your server. For a detailed tutorial there’s some youtube videos on how to set it up.

I’m not sure how great the integrated GPU on AMD CPUs are since I’ve always used a discreet GPU. But I know that people rave about Intel iGPUs that are inside Intel CPUs, in terms of encoding/transcoding. Maybe your CPU is faster at transcoding so I would try disabling hardware acceleration.

My suspicion is that you’re transcoding and that’s where the problem is. You’re focusing too much on the connection speed and I feel like you’re ignoring the transcoding aspect. Transcoding 4K is pretty taxing. Remember that 4K is 4 times the number of pixels of a 1080p.

Test a 4K file that is direct playing and see if you’re buffering on that. You’ll have to find a file that’s compatible with the client device as-is so it doesn’t have to convert/transcode it.

Another reason you could be buffering is the data rate to your media is slow (so it can’t read a 4K file enough)

[Old_Rager]

Again Christian, thank you very much for your time.

With respect to the PLEX server, here are some specs:

• CPU is AMD 7900X which has a CPU pass mark of 51,732 - which from my research should be more than enough to cope with any 4K transcode, yes?
• My C: drive is running on 2 x 1TB Samsung 990 Pro NVMe’s in a raid 0 config - going for as fast a config as possible.
• My D: drive that contains all of the media sits on 6 x 12 TB Seagate Iron Wolf Pro 3.5 HDD in a raid 5 config which runs on an Adaptec 8885 raid controller card offering 54TB of available storage to the system. This is a bit slower (as can be seen in the copying of a 21GB file from the SSD to the raid volume below), but it is the best that I can do ATM.
• The RAM is 64GB of 6000 Mhz DDR5

So all in all, it should on paper be able to complete 1 x 4K transcode on the fly regardless of its size, yes?

The following pic shows the disk copying speed from the raid drive to the SSDs:

The following pic shows the disk copying speed from the SSDs to the raid drive:

So basically, should I really be struggling here from a transcoding perspective - especially when the only thing that this PC really does is to be a PLEX server and nothing else?

Your thoughts here again are really appreciated?

Honestly, I am trying to do my best here, but all I seem to be doing is digging a deeper hole for myself with nothing to show for it…

With respect to my mate’s access, that will take some time to get him to do something at his end. But at least I have a bit of an idea how to go about that now…

[MovieFan]

Have you changed to using the switch? Running Plex over wifi had never worked well, especially when transcoding.

[ChristianKent]

I mean, that’s why you do the tests and monitor the dashboard to see where the problem is. Being “technically” fast enough doesn’t rule out the problem in that area, you’re just guessing. Perhaps it’s fast enough, but you have some settings that are hindering it from performing fully. Look at the dashboard when someone is streaming 4K and buffering and see if it’s direct playing or transcoding (something to which you haven’t even checked). Then look at the progress bar if it’s transcoding to see if it’s “pre-buffering” fast enough. You can tell by the light orange (playhead) always catching up to the dark orange (transcoding buffer).

[Old_Rager]

I have received the Archer BE900 which has 2 x 10GbE and 4 x 2.5GbE ports - and also does quad band. I have hardwired the Plex server’s 2.5GbE, my main PC’s 10GbE, and my TV’s 100Mbps ports into this router via CAT8 cabling, and the Lord of the Rings: Rings of Power S02E01 4k file that I have still buffers, so it cannot be the network, yes?

If it is my CPU which has a CPU Passmark of 71K, how can it be that it doesn’t have enough grunt to transcode 1 x 4K file on the fly?

[Old_Rager]

I will do this in the next 48 hours as I have to move monitor’s around as both my Plex Server and main PC play through the one TV device. Thank you and will let you know when I have done this.

[Old_Rager]

Hey Christian,

I did a bit more analysis. So the following screen scrapes are from me running Plex from my TV’s smart app Plex player which is connected via ethernet to my LAN which runs the Plex server. The following images are taken when running the Lord of the Rings, S02E01.

This first image is where it has stopped three times when trying to play the file:

This second image shows you that when it was stopped, it still had quite a bit of buffer to play but the player just paused as if it was buffering. In this image as well, you can see that the video codec has a direct stream, but the audio codex is being transcoded:

Does this give you any help at all? BTW, the network is never being constrained as at its peak, it was doing around 80Mbps which is within the 100Mbps bandwidth of the TV’s NIC’s 100Mbps.

Your thoughts here - and sorry for taking so long to get back to you with this info?!?

[ChristianKent]

The interrupted green lines in this are a clue. Seems to coincide when the network tries to buffer. Either Plex freezes or something else. It’s not normal for the graph to look like that.

You should upload your PMS logs for when those interrupted green lines appear and maybe someone from Plex can take a look and see.

From all the symptoms my guess would be the client device that’s the problem. But you have a good TV that should be able to handle this stream. So I’m guessing it’s the Plex app on Samsung TVs that’s to blame. If you try to search “4k plex buffering on Samsung tv” you’ll get a lot of results.