IPv6 tunnel broker: unable to accept incoming connections

[maxxer]

I've set up IPv6 via Tunnelbroker GIF interface. IPv6 is working fine for the LAN, outgoing connections are fine and ping6 from firewall and from LAN clients is ok. But I cannot make work the way around. I'm trying to access the firewall over IPv6 but it doesn't work, neither via https nor OpenVPN server. Actually neither traceroute6 or ping6 to the firewall LAN address (routed /64 from Tunnelbroker) work. I'm not even able to ping the GIF ipv6 address (while it works for the server endpoint).

I've enabled IPv6 ICMP on LAN and GIF interfaces with * destination. At this point I'm not sure if it's a firewall config problem or elsewhere... Any hint would be welcome! Thanks