Troubleshooting IPv6 + Aiccu (SiXXS) - Setup partially working

Hello everybody.
I've been able to setup IPv6 through the tunnel broker SiXXS on AsusWRT Merlin 378.56_beta2.
I installed Aiccu through Optware-NG, and setup IPv6 on my router IPv6 configuration page.
My setup is the following:

Connection Type: Tunnel 6in4
Server IPv4 Address: my choosen POP IPv4
Client IPv6 Address: my SiXXS given IPv6 (ending in ::2)
IPv6 prefix lenght: 64
IPv6 server address: my choosen POP IPv6 (ending in ::1)
MTU tunnel: 1280
TTL...

Troubleshooting IPv6 + Aiccu (SiXXS) - Setup partially working