buster's wifi connection is ok for several hours, so i think problem disappear
but after rebooting pc, problem appears again
wifi is provided by hotel, they hide AP somewhere, i don't know where, i think it's reliable
buster can connect to hot spot of cell phone, no problem
zhou@debian:~$ cat /etc/debian_version
10.5
zhou@debian:~$ uname -a
Linux debian 4.19.0-10-686 #1 SMP Debian 4.19.132-1 (2020-07-24) i686 GNU/Linux
zhou@debian:~$