Welcome to this user forum.
Please can you confirm whether its the Complete Wifi from BT
or the Whole Home Wifi system. as your subject title suggests?
Please can you edit your original post and first reply, to change the title to be the same as this one.
I have changed my posts.
There is a special team which is monitoring this this thread.
https://community.bt.com/t5/Home-setup-Wi-Fi-network/Introducing-Complete-Wi-Fi-from-BT/td-p/1901302
It may be worth reading through some of those posts.