We were adding two new plugs to the iOS Tapo app (we already have multiple existing devices working perfectly).

On the phone with the 3.15.106 we spent a frustrating hour factory resetting several times it always hangs on the select icon screen 

We turned off the 5g Wi-Fi and only had the 2.4 GHz Wi-Fi on 

As a last ditch attempt we tried another iPhone which had not updated the App and was still at 3.14.505 and it worked first time after one more factory reset.

the 2nd plug also added with no issue on the 3.14.505 app 

the devices function fine on both apps after the were successfully added but probably around 10-15 attempts on 3.15.106 (both are iPhone 15 BTW)