I recently switched ISP to one that supports IPv6 and I have had nothing but problems. I have had DNS servers going missing from OpenDNS, I have seen all sorts of really weird routing errors and transient problems, its barely usable at all. Linux seems to be more strict about how it handles IPv6 and I found my server couldn't find its upgrade packages because some of their mirrors are broken for IPv6 routing. All in all it was a mess and I turned it off. My ISP must be partially at fault but it was clear Debian was too as was OpenDNS and most of my problems no one could explain what was happening or why.

Not sure what specifically happened in your case, but FWIW... My ISP (Spectrum, previously Time Warner) has supported IPv6 at my location for a decade or more now. And I have been running with IPv6 enabled on my router, and on all my Linux boxen, and have had approximately zero problems related to IPv6 in that time. During that time I've had boxes running various Fedora versions, and PopOS and both have handled IPv6 just fine.

> I recently switched ISP to one that supports IPv6 and I have had nothing but problems.

I was previously with an ISP that support IPv6 and had zero problems.

In fact IPv6 worked "too well" at one point: I had put "facebook.com" in my /etc/hosts file pointing to 0.0.0.0 at one point to reduce tracking. I then noticed I got the little FB icons again at some point and couldn't figure out why things were 'broken' (i.e., not blocking).

Turned out that after IPv6 was enabled I had to add ::1. That blocked FB again. IPv6 made connectivity to FB work again.

I find these experiences really interesting, because in Germany all major ISPs have been doing IPv6 for years and years now.

I dont think any normal person thinks about IPv6 or IPv4 here.

Does running `ip link set mtu 1280 dev eth0` on the client machine fix it?

A lot of servers have somehow managed to screw up their path MTU discovery. People have been using client-side workarounds for this for many years, but I suspect the workarounds are often forgotten on v6. Unfortunately the resulting problems then get blamed on v6.

The other possibility is broken multicast on your local network. Some Wifi mesh APs and "range extenders" just don't work properly. The test for this would probably be to take them out of the network path by connecting directly to the main router via Ethernet and seeing if you can talk to Internet hosts properly.

I couldn't say what your issues are, but I have been on ipv6 (dual stack) on Comcast for over a decade and have had none of those problems. I've always had open source routers and plenty of Linux scattered around the house.

> I found my server couldn't find its upgrade packages because some of their mirrors are broken for IPv6 routing

Have experienced this issue myself a few times. Really annoying.

Usually happy eyeball hides broken IPv6, but its pain to see broken AAAA records on domains that do support IPv6.

I have a IPv6 checker and have a list of broken domains here. https://v6check.miyuru.lk/failed

i have at&t fiber and their ipv6 worked perfectly fine for years, until a one day they started dropping packets like mad and it never got better

exact same issues

centurylink ipv6 via their tunnel

Hehe, it's kind of funny to contrast the IPv6 evangelists and the Linux desktop evangelists push hard for adoption, only for it to fall flat for ordinary users.