I get no ipv6 connectivity on my sgh989 (tmobile usa ver of galaxys2) when on 4g (turning off wifi). On wifi, I get ipv6 (local net has ipv6 connectivity).

Could it be regional... T-Mobile enabling ipv6 for some cities and not others? Or perhaps the current tmobile firmware (mine is 2.3.6, T989, UVKL1) for their sgh989 disables ipv6 for the gsm/utms portion of the radio.