Issue with Matter Device Commissioning – Unable to Join Thread Network

[AkihiroN]

I am developing a Matter device (Thread) using an evaluation board.

When commissioning the device using the Google Home app on a Google Nest Hub, the first evaluation board was successfully commissioned. However, the second evaluation board failed to join the Thread Network.
I have attached the error logs for reference.

To troubleshoot the issue, I modified the Device Attestation Certificate (DAC) in the firmware and attempted commissioning again on the second evaluation board. This time, the commissioning process completed successfully, and the device was able to join the Thread Network.

Questions:

1. Is it expected behavior that the ability to join the Thread Network depends on the DAC when commissioning with a Google Nest Hub?
2. Why does changing the DAC allow the device to join the Thread Network?
3. If the DAC influences this process, what checks does the Google Home app or Google Nest Hub perform regarding the DAC?

I would appreciate any insights or guidance on this issue.
Thank you in advance!

[GoogleDevForum]

Thanks for reaching out. Could you let us know if you are using test Vendor ID (VID) and Product ID (PID) values, or production VID/PID values?

[AkihiroN]

Thank you for your confirmation.
We are using both VID and PID for testing.
We have actually commissioned the following combinations.
First evaluation board
　VID: 0xFFF1
　PID: 0x8004
Second evaluation board
　VID: 0xFFF1
　PID: 0x8000

Please confirm the above.