I try to connect to my Wi-Fi at home and it won’t let me

1. Reboot your Wi-Fi Router by simply turning if OFF for 40 seconds and then turning it back on. Allow 3 - 5 minutes for the Router to reboot. Then try and connect your iPhone 12 Pro Max to your Wi-Fi Network. If that does not work then:
2. On your iPhone 12 Pro Max, open Settings ➔ General ➔ Reset ➔ Reset Network Settings : Once the network settings are reset then you may have to enter the password to the Wi-Fi Networks (previously saved) again. Try connecting to your Wi-Fi network again.

Axel F.

In that very window that you had posted the screen shot of, try setting Private Address option to OFF. Then try again.

Axel F.

If your iPhone connects to a different wifi network (borrow one from your friends or try a public wifi hotspot), restart your modem-router at home.

Regards

Giulio