Also, a remaining issue was sporadic authentication timeout, which usually requests an interface reset to recover: https://git.linaro.org/people/loic.poulain/wcn36xx-monitor.git
To, reproduce the issue, connect with AP and run wpa_cli -iwlan0 scan ; wpa_cli -iwlan0 reconfigure ;
[ 691.799356] wlan0: send auth to b0:4e:26:0b:8a:6d (try 1/3)
[ 692.001410] wlan0: send auth to b0:4e:26:0b:8a:6d (try 2/3)
[ 692.205416] wlan0: send auth to b0:4e:26:0b:8a:6d (try 3/3)
[ 692.409410] wlan0: authentication with b0:4e:26:0b:8a:6d timed out
continues logs come, as workaround is WiFi interface need to do down and up again. as @Loic provided the monitor service as well.
Due to some race condition happened with scan command. In wcn36xx driver, need to handle the serialization of the commands.