Spectator app consistently disconnecting

Hello,

I built an app with Unity, OpenXR. All works fine, and I’d like to add Spectator. I added the prefab (with notifications) for this, and built. I can then find the app from my phone, scan the Spectator QR on the phone, then I can also scan the QR in the ML2. So, all that works just fine. The only thing is that as soon as the second scan is done and the ML2 - phone connection made, then it gets disconnected immediately with a “unstable network” message.
If I enable auto-reconnect, then it just loops between connected/disconnected.
I tried on a different phone. I tried on different wifi, including my home 5Ghz wifi. I tried via a phone hotspot and via a ML2 hotspot, it is always the same.

Am I missing something ?
Can someone provide help?

Thanks a lot,
Arnaud

Unity Editor version: 6000.1.6f1
ML2 OS version: 1.12.0
Unity SDK version: 2.6.0
Unity Spectator version: 1.3.7
Host OS: Windows 11