DLNA sometimes not available and stops after some time

[Aeious]

In the overview I see two active devices. Firefox (Jellyfin Web 10.9.11, User pandi) and [TV]Samsung LED40 (DLNE 10.9.11, User undefined).
But when I go to Devices, there ist only Firefox.
I often see the DLNA device disappear in the overview, sometimes long before DLNA on the TV stops.

[TheDreadPirate]

I'll have to do some testing tonight and/or tomorrow.

[Aeious]

Even when I set another default user in the DLNA Plugin, the active device of the TV still says "undefined"

[TheDreadPirate]

So far I have not been able to replicate the issue with VLC as a DLNA client.

[TheDreadPirate]

Circling back. I had a blip this morning where VLC did not immediately detect my server. I had to refresh a couple times before VLC found my jellyfin sever. What is your client discovery interval and alive message interval set to?

[Aeious]

Client Discovery 60
Alive Message 180

I tried vlc too. It worked without problems over several hours. 
But there was no additional device. Not in the overview not in devices.

Edit: Vlc also needs some attempts to discover the dlna server.

[TheDreadPirate]

You can try reducing those values to 30 and 120?

[Aeious]

I tried the values. Same behavior.

I also tested a lot and I think its a problem specific for the TV. Its the only device that creates a dlna session according to the log.
The behavior of the TV is always the following:
Start of the TV. A DLNA device is shown in the overview of jellyfin.
After 1:30 to 2:00 minutes the Jellyfin DLNA appears on the TV.
After about 15:30 minutes the device in the overview disappears.  
After about 35 minutes the Jellyfin DLNA disappears on the TV. 
The Jellyfin DLNA does not appear again until the TV is restarted.
It doesnt matter if a stream is started or not. If one is started it stops with the disappear of the Jellyfin DLNA 

Al other diveces (smartphone, PC) dont show that bahavior. DLNA sometimes disappear in the windows network for a short time, but I think this is just the way it is displayed in windows. Streaming works fine.

Is it possible that the TV is using an unusual or old authentication method? Strange thing is that it worked fine for a long time before the jellyfin update. The TV was also not updated (its to old for updates ) and other DLNA server are working fine.

[TheDreadPirate]

Its possible. This may be a long shot, but you can check for a firmware update for your TV. Maybe there was an update that fixed this?

[Aeious]

I checked this before. No updates available.

Where can I check if some funktionality was disposed in the last jellyfin updates?

EDIT: I started an issue in Github. I think they know best what changed.

Thank you so much for your help.