Matter over Thread, problem to add Arduino Nano Matter device

[opal estuary]

I am using Home Assistant on Rapberry Pi 4 with a Sonoff ZBDongle-E flashed with OpenThread firmware.
I am trying to add an Arduino Nano Matter device running the provided example light bulb. It works fine with an Alexa Echo, and it worked fine once with HA. But now I am not able anymore to connect it, even though after rebuild everything from scratch, and send creditials on my smartphone.
The procedure is frozen with message "Connectivity check to..." with my Wifi network. My wifi router is configured for IPv4 and IPv6, my network is flat and I do not have any other Thread product at home (Alexa Echo is off now).
What is strange is that at the end the procedure the error indicate a Thread network id that is different (47aa) from the one which is configured in OpenThread Border router (57f1)...
Any idea or help would be very appreciated.

[opal estuary]

I see this error in Matter logs at service start, no error in OpenThread Border Router :
2025-04-09 16:46:01.296 (Dummy-2) CHIP_ERROR [chip.native.DL] Long dispatch time: 197 ms, for event type 2

The Arduino serial monitor :
16:44:34.332 -> Waiting for Thread network...
16:48:16.905 -> Connected to Thread network
16:48:16.905 -> Waiting for Matter device discovery...

[opal estuary]

Did anyone succeed to use an Arduino Nano Matter with Home Assistant ?

Matter over Thread, problem to add Arduino Nano Matter device