Xbox has internet connection but won't connect to online games or store

My son has had issues logging in to fortnite. When he tries it says "the person who bought this game needs to sign in" I went to the Microsoft store to try re install it and it won't connect to the store. It says to test internet connection. When I do it's all good. Same issue on my Xbox I can't play any of my online games even though I am signed in with the account that purchased them.

:)