You didn’t setup your network correctly, I would say.
I have an access point and the router itself. Both Wifi senders/receivers are on. Both have a different name. But both are with all B&o devices in the same subnetwork. All must be in the same (sub)network to work correctly.
If I connect my iPhone to the AP or to the Router, the accessibility to all B&o devices stay the same.
Did you create different subnetworks one for every AP?