Yeah, IPv6 is shut off on my Google Fiber router. Stuff on the Internet breaks when it’s on (last tested three or so months back when they sent me a new router).
When we first got Fiber, years ago, Amazon’s store was one of the things that broke until I turned off IPv6. Wouldn’t load at all, on any device on our network.
Works fine for VPNs and such, but I don’t talk to the Internet with it, because my experience has been it’s terribly unreliable.
I'm curious what breaks with IPv6 on. I've been running IPv6 dual stack for over a decade at home and pretty much never have any issues. I think I've run into a prefix change get bugged on my router's announcements that required a reboot, but that's like 2 times in the last 10+ years and I'm not 100% sure that was truly the issue. My phone is pretty much always has an IPv6 address and pretty much never has IP-related connectivity problems. I'm not using Google Fiber's router though, so that could be the complication.
The typical behavior is that DNS returns an IPv6 address, then whatever-it-is sits there until a timeout, because it’s simply not being routed. I’ve not investigated further because turning off IPv6 fixes the problem and breaks nothing (that I care about). Anything that only returns an IPv4 address from DNS works either way.
My cellular connection supports IPv6, but testing sites report it’s misconfigured in a bunch of ways. I don’t see problems in practice, though. But on my home network, it’s turned off.
This is what I was thinking about with the prefix issue. I've encountered this issue like twice and rebooting my router ended up with a different prefix, so it seems more like my router just didn't get the new prefix and thus kept handing out the old prefix to everyone with SLAAC and thus wouldn't get routed right.
When we first got Fiber, years ago, Amazon’s store was one of the things that broke until I turned off IPv6. Wouldn’t load at all, on any device on our network.
Works fine for VPNs and such, but I don’t talk to the Internet with it, because my experience has been it’s terribly unreliable.