Finally, I have found the reason for this problem. It is caused by the Microsoft update Kb5014699, which makes the wifi hotspot function fail. After the new update distributed by Microsoft this week, the problem has been fixed. Thanks for your support!
Thanks for your reply. Either I turn on or turn off the diagnostics, the same error ‘connected, display off’ shows up. Moreover, I tried to turn off Videowall and it still gives me the same error. The debug log without Videowall is in the attachment.