Error message 104101 while connecting using browser/zoom client on Mac/Win and iPhone on 5G

My nephew have a very weird problem that when he join the school zoom meeting
He would join the meeting using his chrome browser on Windows as he occasionally jot this 104101 problem
But somehow when he got this message
He try to rejoin using the follow devices:
1) The same Windows Chrome brower using same WiFi

2) The same Windows Zoom client using same Wifi

3) The another Mac Chrome Browser and Zoom using same Wifi

4) The Chrome Book the school provided for him to troubleshoot using same Wifi

5) Using iPhone and Android phone using same Wifi

6) Using iPhone and Android phone using 5G

All these device cannot join back in after receive the 104101 problem. I have helped him to turn off the Windows Firewall and the Anti-virus software during the problem and it didn't help at all. And I am 100% sure there are no firewall in their network or their ISP (There are no such service of the ISP)

What is strange is when he have the problem...he cannot join the other teacher meeting (using different meeting number and different Zoom account) the whole day! But he can join my company and personal Zoom meeting.....

Anyone have slight idea what is going on? I am a Cloud security engineer and I have been doing network security for 20 years and it is one of the weirdest problem I ever met.