This is a follow-one from 6in4 IPv6 Tunnel natively on Technicolor TG582n, which, as several of us found, is no good if you use Google Chrome as a logged in user, as something about the SYN packet to Google crashes the router (only took 3 months to figure it out!) So I have a spangly new Sagemcom 2704n here on the desk - the question is, can I try tunneling 6in4 with someone like sixxs, on this router? I had a forum search - might have missed it but turned up nothing.
My initial impression was that the router is a bit c*** (so I quickly replaced it with a VyOS model). If you're going to get it to do something interesting you might need "expert mode" - http://192.168.1.254/expert_user.html ;