Still intermittently will not connect
Why does my iphone not always connect to the internet via my wi-fi?
iPhone 11 Pro, iOS 14
If you read the information in the support document that you came to the forum from, you will see there are a number of different reasons when you may have wi-fi connection issues. You need to follow all of the different steps there and test for a bit to see if they work. Otherwise, you would need to contact Apple Support to set up service for them to examine your phone.