Hi, there are many threads on this topic, however thought I would post my experience separately rather than pick a random existing thread.
Finally got ipv6 correctly configured to work with setup of-
BT FTTP, Openreach modem, TP-Link Deco X60 router with 2 x satellites.
After several configurations this one has proven to work, having checked the usual ipv6 web browser validation sites such as test-ipv6.ocm; also my laptop and iphone 13 connetion-
Connection type: PPPoE
Sync IPv4 Account: On
Prefix Delegation: On
DNS Address: Auto
Assigned Type: DHCPv6
Hope this helps someone!