Video playback stuttering

[Unkn0wnUs3r]

Hey guys,

i just switched to jellyfin to give it a chance replacing my plex server.
Currently i got a i5-12400 along with a nvidia geforce rtx 3060 (pcie passthrough to my docker vm).

Inside my docker vm i setup several containers. One of them is jellyfin along with nvidia runtime. Docker containers and transcoding happens on a ssd array. Video files are on my hdd array, mounted to my docker server.

If someone streams a movie (remote), everything seems to be fine (Video File 9GB; HEVC). If someone wants to watch another movie, stream 1 und 2 stutters and its nearly unplayable.

I got an average CPU usage of like 30%, Nvidia GPU is being used (checked with nvidia-smi), RAM is like 4 of 16GB used.

Can someone explain to me why this is happening? I didnt get any issues with plex under a windows vm, streaming to 4 ppl simultaniously. Network upstream is peaked at around 20mbit (if i look onto my unifi udm), my connection can handly up to 40 mbit upload.
I like the idea to share gpu ressources, this i why i want to give jellyfin a try.

Logs attached.

BR Manu

[Unkn0wnUs3r]

Update: it is also stuttering while only one person is streaming remote.

[TheDreadPirate]

The transcoding is happening plenty fast. So that isn't it. Are all of your clients remote relative to the server? What is your max upload? 40Mbps? Do you have other apps consuming upstream bandwidth? The 1080P transcode log you attached indicated that the output bit rate was ~20Mbps.

[Unkn0wnUs3r]

Thank you for your fast reply.

All of my clients are near to my server. No other apps consuming bandwith. On my firewall i got a peak usage of 20 mbit (combined). I have 40 mbit available.
For incoming traffic, i setup my firewall as an exposed host in my router. I set up port forwarding 80/443 to my reverse proxy (nginx), which encrypts the traffic and sends to my jellyfin container on the docker host.

[TheDreadPirate]

So your clients are local? As in on the same LAN? Are your clients using a domain name to connect to your server? Do you have NAT loopback enabled on your router?

[Unkn0wnUs3r]

No, my clients are a few kilometers away, streaming with different devices like apple ipad or webbrowser from my domain media.unknownworkspace.de.
At home, i also stream from my domain - which is kinda useless because the traffic will also go through the www.

Cant find any options regarding nat loopback in either my firewall nor my router.

---

Speedtest inside an extra docker container.

[TheDreadPirate]

It may also be called NAT hairpin or simply Hairpin. But not all routers support it. NAT Loopback is only needed if you access it from the same LAN, which is sounds like you also do. NAT loopback/hairpin keeps data local if you use your domain name instead of going out to the Internet only to come back to the same place.

For testing, can you port forward port 8096 and access Jellyfin directly without the nginx proxy?

[Unkn0wnUs3r]

I exposed port 8920 cause of https redirection.
Video playback to my web browser (computer connected to lan) is also stuttering. But it is better: just 4 short breaks in 3-5 minutes - yet not optimal.

[TheDreadPirate]

Both of these transcodes are over 80Mbps. This is sounding like a network bandwidth issue. In Plex did you have a bit rate limit set? And you don't have one in Jellyfin (yet)?

[Unkn0wnUs3r]

AFAIK Plex is handling out the available bandwith in some way and sends it back to the server to get the movie transcoded or direct played.
In Jellyfin, i set a bandwith limit per stream outside my network of about 20 mbit.