I am seeing a similar issue to this one, although the only website I can not visit via ipv6, (of the ones I tried) is the hurricane electric web sites. I have 2 tunnels setup. 1 tunnel is from work the other from home. From both of the tunnels I am able to ping and be pinged, tracert, etc. At work the tunnel is setup directly in windows. At home I am running dd-wrt with radvd giving out the ipv6 addresses. It all works well unless I try to access this website.
I successfully visit ipv6.google.com,
www.sixxs.net,
www.whatismyipv6.net, and other sites. The ones that tell you where you are coming from show my an address from my ipv6 /64 subnet that I am giving out from my dd-wrt. Hurricane electric never comes up.
Testing from the command line I can ping the ipv6 address of tunnelbroker.net and can tracert to it. I have verified that the address I am getting from work and at home are the same. I can also ping and tracert from work.
The next test is telnet to the ipv6 address port 80. I then type a few characters and hit enter. This just sits there at home, but works beautifully from work. Next I try the same with the ipv4 address. This works fine on both systems. I am farely sure I don't have any firewalls setup to block just port 80 from tunnelbroker.net through my firewall in dd-wrt. BTW, this same blockage of tunnelbroker.net is happening from 4 different machines behind my dd-wrt router. Does anyone have any ideas? I have solved it for now by putting the ipv4 address in the hosts file, but that doesn't really solve the issue.
Thanks