Issue connecting Apple TV to wifi

I am trying to connect my Apple TV to our upgraded wifi and it's impossible. When I go to the wifi (Settings General Network) and click on our router, the page double clicks and reads: 'There is a problem connecting to the network - The wifi password you entered is not correct. Try again (-100)'. As the page double clicks through, there is no option to enter a password or forget the network.

Reading through other posts, fellow sufferers have suggested changing the router from WPA3 to WPA2 but my wifi company says that would affect the internet connection of all of the other devices in the house.

What's really weird is that it's only my router affected. When I click on any of the other wifis available, they all go through to a password page.

So far I have restarted the Apple TV box and the wifi with no luck. I haven't reset the Apple TV box yet.

Help!