Same here. I’ve tried: 

• rebooting the modem
• rebooting all Sonos products
• restarting my gateway
• deleting and reinstalling the app
• chatting with a Sonos rep (got disconnected and then they were closed)

I know my wifi password is correct, but it won’t connect.

Try disabling Airtime Fairness for both 2.4 and 5GHz bands in the router’s settings. If this doesn’t work, you may have to revert back to the previous firmware on the router.

And contact ASUS with the issue. 

ASUS don’t have a great track record with Sonos compatibility. Looks like that hasn’t changed.

Ok solved the damn issue. I did all that Washington written on different page nothing helhed. In the end what helped was to reset every Sonos speaker I have, and reconnect through the Sonos app.

Thanks for the tips.

One wonders what words were autocorrected….