@Sunshine, you asked:

1) Hi, is your network topology like this: LAN cable from ISP---Switch----Archer AX50 Router, or LAN cable from ISP---Archer AX50 Router---Switch---client devices?

--> Switch is BEFORE the WiFi router, yes.

(I know usually switch should be after the router but I put it this way to avoid router damage by lightning.)

2) You mean sometimes, internet stops working and recovers after restarting the switch, but the WiFi of Archer AX50 will be disabled automatically?

Please confirm if the WiFi is enabled and visible before you restarting the switch.

--> Yes, and yes. Issue is with router, not the switch.

(Also, I am not restarting just the switch, no. I am restarting BOTH the switch as well as router.)

3) In addition, please check if wireless schedule is enabled on Advanced->Wireless->Wireless Schedule page, if so, the WiFi will be off automatically during the scheduled off time.

--> This is only from 2 AM to 9 AM, problems happen outside this interval.

4) In addition, there is a WPS/Wi-Fi button on back panel of the router, you could also press and hold the button for 2 seconds to turn on or off the wireless function of your router.

--> Sorry but this does not help any! I need a real fix, not a workaround.