RT-AC5300, wireless devices could not connect to both 5GHz channel

I am having issue with my RT-AC5300. I have recently upgrade to Merlin 384.7 and found out both 5Ghz channel does not work properly (2.4Ghz works fine). I can see the SSID but I could not connect to it. It either keep show wrong password, no internet access or could not get DHCP from the router.

I have done factory default (both restore and initialize). Still could not fix the issue.

Is there anyone solved this issue before? Please advise me how to fix it.