SOLVED: Kodi does not register Serviio on Android boxes

I have three Android smart-tv-boxes (one of them is Xiaomi Mi Box), and also Linux PC.

I upgraded my movie server (Linux Ubuntu Mate 20.04.1), and now for some reason my KODI-players do not register to Serviio. (they do not show in connecterd devices)

I am using Serviio 2.1

My Amplifier and Blu Ray-player does register as connected devices.

On my old movie server every device with KODI registered and worked just fine.

So there is some conflict between KODI and Serviio. But what?

Any Ideas where to start?

[atc98092]

Conflict? Doesn't seem to be. I use Kodi on two different Nvidia Shield players, and both see Serviio without an issue. You do have to have uPnP support enabled in Kodi, which is buried in one of the Expert menu settings. But I use it every day with both Shield players without a problem.

I have not touched my android-boxes, and they worked before with older movie server, that has older Linux, and older Serviio.

Luckily I have this older Serviio on my hard drive, and I will test it. If the problem is cured, then there is a bug in new Serviio

[atc98092]

No, there's no bug in 2.1. I have it on both of my media computers. Both of my Shield players work with it just fine. Have you made any changes at all with your home network? Are the Android players on the same network segment, and not being blocked by a router or WiFi setting?

Solved it!

Only difference physically was that that old server was connected via LAN-cable, and this used WLAN.

I turned servers wifi off and connected this to LAN-cable and everything works. (Faster anyway, so also better)

So it must be some setting in my wireless router, as you suggested