Unable to add payment card because my phone thinks I am not connected to the internet.

When adding a card, my phone gives me an error message which says “Could not connect to Apple Pay - make sure you are connected to the internet”

I am connected. I have 5G+. All my other apps and downloads work. I can surf the web, send WhatsApp messages, watch YouTube etc.

The other thing that isn’t loading is my Apple account, when I click on Settings> Sign in & Security > it gives me a message that says Account Details Unavailable

In my Apple family, I also see a red error message saying “A network error has occurred”

Does anyone know how to trouble shoot this? I’ve already reset my phone & mobile data.

Any help appreciated as I don’t live close to an Apple shop!