[swift]

Is the hardware you're talking about the network equipment controlled by the ISP, or the routers and modems in customers' homes? I'd be surprised if the former hadn't been IPv6-ready for many years now, but I can imagine many customers are still using ancient hardware left over from when they first signed up for service.

[tsomctl]

If you have cable, a number of providers have been making customers upgrade to the newest modem. A single old modem that doesn't support docsis 3 will slow down everyone in your neighborhood.

[curiousGambler]

Really? Interesting... can you elaborate/provide some reading?

I'm a software engineer with a smidge of basic networking experience so not completely clueless, but definitely inexperienced with DOCSIS and this sort of residential networking stuff.