Unable to bind ipv6 address when starting jail (unknown error)

[Beni Grind]

Hey all

I've had this issue for some time now but never got around to post it here. I'll post the error messages I get from knot DNS, however the issue is more general and happens in a similar fashion in my nginx and my hedgedoc jail.

I have a vanilla alias jail (converted from iocage) configured dual stack with an IPv4 and an IPv6 address on the same physical interface. Inside the jail I run knot as a regular service. When I start my jail using
service jail start dns
the jail is started however knot fails to start within the fail. In /var/log/daemon I see the following error message for IPv6 - IPv4 seems to be fine, though:

Apr 19 09:38:30 dns knot[10211]: info: binding to interface XXXX:XXXX::3@53
Apr 19 09:38:30 dns knot[10211]: error: cannot bind address XXXX:XXXX::3@53 UDP (unknown system error)
Apr 19 09:38:30 dns knot[10211]: critical: failed to configure server

When I then enter the jail with
jexec -u root dns
and start knot manually
service knot start
it starts just fine and works.

That's the content of jail.conf for this jail:

exec.start = "/bin/sh /etc/rc";
exec.stop = "/bin/sh /etc/rc.shutdown";
exec.clean;
mount.devfs;

# Dynamic wildcard parameter:
# Base the path off the jail name.
path = "/jails/$name";
exec.consolelog = "/var/log/jail.$name.console.log";

dns {
  host.hostname = "dns";
  ip4 = "new";
  ip4.addr = "ix0|x.x.x.53/27";
  ip6 = "new";
  ip6.addr = "ix0|xxxx:xxxx::3/64";
  persist;
  allow.raw_sockets = 1;
}

Do I need some code to delay the start of knot? Where would I put this? What confuses me is that it works finde for IPv4 but not for IPv6. The OS of the machine and the jail is FreeBSD 15.0 but it also happened with iocage under FreeBSD 14.3

Let me know if I left out an essential piece of information.

--beni