as my ISP is Unitymedia, I am stuck with a DSLite internet connection.
Therefore, I use a portmapper to map a IPv4-address (with a specific port) to my IPv6-address (with a specific port) of my server. This looks something like this:
IPv4 address provided by portmapper is 123.456.78.9:12345 and if I connect to that, the portmapper maps it to my server IPv6 address xe12:323a:xxx:xxx on port 80.
With this constellation it is possible to reach my webserver via IPv4.

Now that TeamSpeak3 seems to be supporting IPv6, I wanted to do the same thing.
So I set up a server. Connecting to it in my own LAN works seamlessly (all via IPv4, as the client is not supporting IPv6 yet(?)).

But as soon as I want to connect via the portmapper, I can't connect.

The portmapper has the option to see if the ports are reachable, so I tested all the ports, that TeamSpeak3 uses (10011, 30033, 9987).
For the TCP-ports I get the notification, that they are reachable, but for the UDP-port (9987) it is not the case.

In another thread here it was said, that this is due to the cause that UDP-ports do not respond and it should work nevertheless, but obviously it does not. ;-)

So here is the question:
Should this be possible at all? I am asking this, because everything seems to be working (ports are open and forwarded and I am able to connect via LAN). Maybe the support for IPv6 is not as far, yet? Or maybe I am just doing something wrong.