FritzBox not picking up the tunnel IPv6 address

[user3636]

Hello community,
I setup a tunnelbroker interface on a LinuxBox behind my Fritzbox so I can expose just the IPv6 address.
Following the instructions provided by tunnelbroker for linux.
However the FB does not want to pick the

2001:470:XX:XX.XX::2
address.
Does anyone please what I am missing ?
thx, user3636

[cholzhauer]

Can you be a little more specific?