Bridging IPv6 LLA into docker container

Hi,
I am successfully running pihole in a docker container with both IPv6 and IP4 networks defined in the Compose YML. This is running on RaspiOS . The IPv6 network within the container is defined with a ULA (fd01…) subnet and has two ports bridged into the container, port 80 for the browser admin and port 53 for DNS queries.

The IPv4 network works as expected, however, I have to use the GUA (2001…) of the Pi server in order to access the container via IPv6. it would appear that the IPv6 bridge does NOT support packets received via the LLA (fe80…) of the host machine.

Is anyone aware of a configuration or technique which would allow the IPv6 LLA to bridge into the ULA subnet inside the container?

Thanks
mhoam