As I wanted to work with IPv6, I used UPNP_AddPinHole and ended up with it returning 606 ("Authorization required") After digging into it, I found out that my IF has 2 IPv6 addresses. A "Normal" one ...

i'm trying to use UPNP_AddPinhole to add IPv6 pinholes. However, this fails with 606 (Action not authorized). However, i try to open a pinhole port on the 2a10:.... address, that is globally routable.