I'm running the Homeassistant Docker container in host mode. So it should work, but it doesn't. Hm Hm.
I get the same problems as the other forum members told
Hey, did you resolved your problem?
I got the same error at my side, that I can ping these link local addresses easily from my windows machine, Mac and any other devices but not in my HA docker container on my Unraid server.
A Gateway is setup in my UniFi network and everything IPv6 related works seamlessly outside of unraid.
Thanks for your answer.
Cheers