…or not. Apple released the v6.1 update for the Airport devices including Time Machine. Unfortunately this update ‘breaks’ IPv6 is you were using an Ipv6 tunnel via HE’s tunnelbroker.net. The fix is simple. Log in to both your Airport and the tunnelbroker.net website. On the last one you should look for your ‘Routed /64’ address. Fill this address in the ‘IPv6 Delegated Prefix’ field of your Apple Airport and IPv6 is back as before.

Apple Airport Extreme IPv6 configuration