IP6 configuration for direct access methods

Hi all,

does anyone have some experience in how to configure the combination from WDMycloudHome and a FritztBox7490 on IP6 to use direct access instead of relay?

I configured UPnP so that MyCloudHome should be able to open ports, but it doesn’t.
I opened the firewall for IP6 prefixes, but still no direct access.

Can anyone help?