Idle clients

[AlienBulls]

Hi community,

Yesterday, when I checked my traffic usage on my ISP modem, I noticed that I had around 3.6 TB upload and 2 TB download. Of course, the download traffic includes my YouTube watching, web browsing, Steam, etc.

Currently, I have 8 friends who access my Jellyfin server via Tailscale, but only 2-3 of them actually stream content actively, and I’ve never seen more than 3 people streaming simultaneously. My Lenovo M710q Tiny handles everything well with its 32 GB RAM and hardware transcoding on the Intel i7 7400T. Jellyfin is installed directly on an Ubuntu 24.04 server and my library is about 4 TB.

Yesterday evening, I installed vnstat to track traffic a bit more closely. This morning, I noticed that overnight roughly 600-700 MB was uploaded every hour. I then saw that one client (a Fire TV Stick) from a friend was still connected, even though they weren’t streaming at the time. I’ve seen the same behavior with another friend who uses an Android TV. I suspect the app just isn’t closing properly in the background. After I blocked the Jellyfin user on the friend’s Fire TV Stick, the upload traffic dropped.

Unfortunately, I haven’t found anything similar on Google or in the forums, so I asked ChatGPT what could cause high traffic even when nothing is being streamed. ChatGPT suggested it might be due to screensaver images (which I doubt) or poor image caching (for example, if the Fire TV Stick doesn’t have enough storage). I asked my friend, and since he only has Jellyfin and Netflix installed, I don’t think it’s a storage issue.

The traffic doesn’t really bother me, but it seems unnecessary, and I would like to avoid it if possible.

Has anyone else experienced something similar or know what might be causing this?

Edit: In Jellyfin dashboard I see his client and a TV show at minute 7:46. It's paused.

[toytown]

So as i have an idle client (looks like they paused a show 2 days ago) i got curious about your findings and thought i would have a look at the data from my firewall, whist logged into jellyfin over my LAN to make sure nobody fired up a show etc. I reset my firewall counters for port 8096 and after 10 mins i see that i have received 2.2MB and transferred 91MB.

So it looks like i would also be sending about 550MB of data an hour for a client which is doing absolutely nothing. Not an insignificant amount for people with data caps/lower upload speeds/a few idling clients. The show itself is only 1GB (about 20mins long) and extrapolating the data means it might have already used 26.5GB of network traffic.

I'll report back after a longer monitoring period if none of the other family members start a show.
EDIT - after exactly 1hour its 10MB received and 408MB transferred.

[AlienBulls]

I've noticed in NetHogs that the client downloads data at certain intervals. I asked my friend to disable the screensaver, which displays movie or TV show information and cover art, to see if that's the cause. I'll get back to you with the results.

[toytown]

I asked my friend to disable the screensaver

At least from the admin dashboard, my user has screensaver set to "None".  It's possible that this isn't reflected on the client though.  The client like yours is also a firestick.

[AlienBulls]

So if I use:

Code:

sudo ngrep -d any -W byline '^GET |^POST |^PUT |^DELETE |^HEAD ' port 8096 | awk '/^(GET|POST|PUT|DELETE|HEAD)/ {
    cmd = "date \"+[%Y-%m-%d %H:%M:%S]\"";
    cmd | getline timestamp;
    close(cmd);
    print timestamp, $2
}'

I can see this:

Code:

[2025-05-28 13:13:52] /Items?maxOfficialRating=13&hasParentalRating=true&limit=5&recursive=true&includeItemTypes=Movie&includeItemTypes=Series&imageTypes=Backdrop&sortBy=Random&enableTotalRecordCount=true&enableImages=true
[2025-05-28 13:13:52] /Items/d4a4c38c-55fe-50e0-de47-b159a72174d8/Images/Backdrop?tag=702167edecf78c32e2687ae19b351e5c&format=Webp
[2025-05-28 13:13:52] /Items/d4a4c38c-55fe-50e0-de47-b159a72174d8/Images/Logo?tag=e903fc6e0da327bcc55575802de01dfd&format=Webp
[2025-05-28 13:13:56] /Sessions/Playing/Progress
[2025-05-28 13:14:11] /Sessions/Playing/Progress
[2025-05-28 13:14:26] /Sessions/Playing/Progress
[2025-05-28 13:14:32] /Items?maxOfficialRating=13&hasParentalRating=true&limit=5&recursive=true&includeItemTypes=Movie&includeItemTypes=Series&imageTypes=Backdrop&sortBy=Random&enableTotalRecordCount=true&enableImages=true
[2025-05-28 13:14:32] /Items/327eccb3-04cb-4233-1fb4-4dfbdf7b9445/Images/Logo?tag=f59cc62c634a5e11203cb715b92b8c8f&format=Webp
[2025-05-28 13:14:32] /Items/327eccb3-04cb-4233-1fb4-4dfbdf7b9445/Images/Backdrop?tag=1ee735aec13175f90ffbf7bb904fd4f2&format=Webp
[2025-05-28 13:14:41] /Sessions/Playing/Progress
[2025-05-28 13:14:56] /Sessions/Playing/Progress
[2025-05-28 13:15:04] /Items?maxOfficialRating=13&hasParentalRating=true&limit=5&recursive=true&includeItemTypes=Movie&includeItemTypes=Series&imageTypes=Backdrop&sortBy=Random&enableTotalRecordCount=true&enableImages=true
[2025-05-28 13:15:04] /Items/62fb5b3d-c3f8-993f-d609-9f5ef1d43f60/Images/Backdrop?tag=aa50354d01b549f7cc1869e9a5f151c7&format=Webp
[2025-05-28 13:15:04] /Items/62fb5b3d-c3f8-993f-d609-9f5ef1d43f60/Images/Logo?tag=143bb141eedcce60346720eaa6acb34d&format=Webp
[2025-05-28 13:15:11] /Sessions/Playing/Progress

If I check the filesize of the backdrop images it reaches from 900kB to 7.1mB. So this could really cause the traffic over time.

[toytown]

If I check the filesize of the backdrop images it reaches from 900kB to 7.1mB

This also kinda ties into another post i made yesterday.  Some of the backdrop images are originally stored as 2160p images at 2MB, but they are then cached on the same drive as a 12MB image (6x increase).  Not sure why jellyfin doesn't just serve the original (ever so slightly better quality and much lower sized image)?

Edit

So this could really cause the traffic over time

Yes i think you solved it, i used tcpflow to get the same data you did and i just see a bunch of backdrop requests all the time in the log. I think some logic needs to be used to stop it sending bigger files than the original backdrop though.

If the original URL request has "&quality=xx" set, then the requested can be reduced, so the logic is there in the code and could be forced by using nginx or a similiar proxy. Hopefully the devs allow it to be set in the admin dashboard in future.

[AlienBulls]

Yes i think you solved it, i used tcpflow to get the same data you did and i just see a bunch of backdrop requests all the time in the log.  I think some logic needs to be used to stop it sending bigger files than the original backdrop though.

As we had already suspected, it was the screensaver. My friend disabled it, and the hourly traffic has gone down again.

I have to say, the setup is a bit odd. He’s using an old TV without a USB port, so he connected his Fire TV Stick directly to a USB power adapter. That means when he turns off the TV, the Fire TV Stick doesn’t automatically turn off as well. It's also strange that the Fire TV Stick apparently never goes into sleep mode, but oh well.

The whole point of the screensaver is to cycle through images, of course, but it would be nice if you could set a time limit server-side (and the client actually respected it), because after several hours, it really starts to seem pointless.

That said, I probably wouldn’t have noticed any of this if it weren’t for the main issue: the images are way too large or poorly compressed. There’s definitely something wrong there.

Anyway, I’ll just ask my friends to disable the screensaver, and then the matter is pretty much resolved for me.

Thanks toytown for helping!

Edit: Maybe it doesn't go to sleep because he didn't stop the playback, he just paused it.

[toytown]

That said, I probably wouldn’t have noticed any of this if it weren’t for the main issue: the images are way too large or poorly compressed. There’s definitely something wrong there

Looking at the source code the imagequality is set to 100 (its max value), which is why it produces big files. I personally think it should default to 90 (also used elsewhere in the code). Ideally though maybe a server side option for those who have limited upload.

Thanks toytown for helping!

Anytime you figured it out by yourself anyway! Hopefully give the devs something to look at