You should do a full reset to defaults after flashing new firmware (when you're seeing issues like now) and then use the defaults to check if things work as expected.
If they do, change one setting/feature or option, reboot the router, and continue doing so until your network is set up the way you want.
The spaces in the SSID, the WiFi Agile Multiband, the Control Channel on Auto, the Authentication Method, and the WPA Encryption all look 'wrong' to me.
Note that in my experience, flipping settings back and forth isn't the same as leaving them alone in the first place (after a full and proper reset). Do a full reset and follow the suggestions I've made above. For the fastest path to a stable router/network.
[Wireless] ASUS router Hard Factory Reset | Official Support | ASUS Global
Fully Reset / Best Practice Setup / More
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