HA doesn't accept incoming connections (only if custom domain used) via IPv6

Hi there,

I am coming from using HA with nginx proxy manager, a custom domain, a bunch of subdomains successfully and secure on IPv4 to a totally chaotic migration to IPv6.

Maybe someone can help here:
I am forced to use HA for external access via IPv6 since I do not have a public IPv4 anymore since our provider switched to a CGNAT for IPv4 and only provides public access via IPv6.

After playing with 6tunnel I made the decision to use the cloudflare proxy to have IPv4 traffic forwarded to IPv6 as it’s free and pretty reliable and more secure (besides the fact cloudflare can read your unencrypted traffic) than running 6tunnel on a microserver somewhere…

Directly accessing my HA via it’s native IPv6 adress like https://[2a00:xxxx:41c4:xxxx:612c:xxxx:c53a:xxxx]:8123/ works fine. I can access the system pretty well.
Now, since most Networks I use while out of home are still IPv4 only I was looking to bind it back to the custom domain I have and forward the traffic.

Now the issue arises that when traffic is being routed via cloudflare onto the custom domain, HA doesn’t react. With tracert I can see the traffic arriving at HA locally, but HA doesn’t react to it.
It simply times out.

I am certain this might be as I might have not configured something. But I wonder what is missing?
IPv6 directly via the pure IP Adress is working well. Just when the custom domain is being used, and therefore the IPv4 → IPV6 proxy, traffic is being blocked by HA.

Any idea what to try?

I switched in between two instances of 6tunnel and cloudflare. Result is always the same. So there is no issue in this, since I made some tests with other stuff like NAS and it works fine. Just HA seeems to be reluctant to accept it’s domain-bound traffic.