Scott Reyling 's suggestion is work for me. Thank Scott Reyling much.
After doing all the others things not work, i do the following:
Set on fiber Modem wifi setting (my fiber modem wifi is huawei hg8045a)
-set Authentication Mode is WPA presharedkey
-set Encryption Mode is AES
- chanel 11 or 6 (change between them)
(sometimes you need change Mode : 802.11b to others and reverse)
I must take time to observe this( whether wifi is stable) but at first it works for me now