Collabora Container with IP V6

[F_Wechsel]

I am running Collabora in a LXC Docker Container exclusively with an IPv6 address.
So far the server seems to work:

With IPv6 I get back an Ok from the server in my browser window.
I am also able to login.

Unfortunately Nextcloud does not seem to accept an IPv6 address in the URL field to activate the own collabora hosting.

Any ideas how this problem could be solved? I already tried to create a cloudflare proxy and cloudflare tunnel, but they seem not to work too.
As I have no additional IPv4 free available, it would be great, if there would be a solution for the use of an IPv6 address.

Help would be nice!

[wwe]

Please follow the Collabora integration guide. TLS and correct public DNS is the key. IPv4 or IPv6 is not really important I remember people successfully integrated using IPv6-only (review ipv6 topics)