Ugh, Centurylink. Their networks, both DSL and Fiber, support IPv6 but you need to go into the router config and explicitly enable it which is why they show up as 0.5% IPv6 supported in that first link despite every other top-10 US ISP having at least 50%. I've enabled v6 on my home connections with them on both DSL and fiber and I've had absolutely no problems with it. I wish they would enable it by default with their consumer network equipment.