> And then random stuff just doesn't work. Various websites hang, various widgets just don't load, etc. Then I turn it off and everything gets better again.

Before I switched ISPs a few weeks ago to one without IPv6, I was with an ISP with IPv6 (dual-stack) for about five years and had zero problems.

In fact it worked 'too well' initially: when I was still IPv4-only I had put a bunch of Facebook domains in my iMac's /etc/hosts file pointing to 127.0.0.1 so that all those little icons would stop loading. At some point I noticed they were back.

After some head scratching over a day or so I realized that Facebook was IPv6-enabled, and so the icons were loading because AAAA records were working. Adding ::1 for Facebook in hosts fixed things.

One of the security issues with dual stack. Your attack surface is twice the size, and human error means you are more vulnerable.

Still unsure of the benefit of dual stack, but there are numerous costs.

You have some misconfiguration on your local network. It's hard to tell from your description, but I'd guess maybe you don't have the firewall rules configured for IPv6 or something. Breakage is extremely rare on the live web. I can't remember the last time I found a website that was only breaking on IPv6.

The other common mistake is blocking ICMPv6 completely. This creates a really broken IPv6 stack!

edit: I've been running dual-stack with Windows, macOS, iOS & Linux for at least a decade now - I think it's closer to 20 years than 10! I've never seen it be like the parent post for my personal use, but I have seen it broken like that in places I've worked with incorrectly configured routers/firewalls.

edit 2: this isn't a good idea for v4 either, but it's less broken than v6!

> You have some misconfiguration on your local network

I’m sure I do. But that’s sort of the point. I only use standard commercial hardware with the default config.

If that doesn’t work out of the box, what chance does someone who doesn't have my decades of networking experience have in fixing it?

Granted I’m probably more sensitive than most because I know what network issues look like. Most people probably just think some things are slow sometimes.

My ultimate point though is that this is probably a barrier to adoption.

I think there's largely three groups that home users fall into here:

1. people who just use the router their ISP provides

2. people who go and buy off the shelf consumer routers/wifi - eg Netgear, Linksys, TP-Link

3. the kinds of people who run home labs and use small/medium business targeted routers/wifi like pfSense, VyOS, Unifi, Mikrotik, or even things like Juniper SRXes etc.

The first group will get a 'blessed' and hopefully well tested IPv6 configuration when their ISP rolls it out, and I'd expect minimal problems there. Certainly haven't noticed anything big in the UK with some of our biggest ISPs rolling out v6.

The third group will inevitably have teething troubles, but v6 works okay on those kinds of platforms once you know how to configure it, from my experience.

The second group is where a lot of the pain will sit, imo. I've found consumer routers have really bad IPv6 implementations (things like broken prefix delegation, broken firewalling that can't be changed, IPv6 negotiation not working over PPPoE, weird RA settings, etc). The firmware on these kinds of devices is usually not great, and things like hardware acceleration engines in router CPUs are also frequently missing acceleration paths for v6 for things they already accelerate for v4. It will get fixed eventually, but it's going to be a pain point for a lot of years to come.

I agree with you, this is a great assessment. And of course I'm in group two. I'm sure it's the router's fault, but other than IPv6 it works great, so there isn't really much reason to change it or dig into it. I'll just wait until I actually need v6 and then worry about it.

And, each group is probably an order of magnitude smaller than the one before it - nearly everyone just uses their ISP's router.

A small number of people use routers you can buy from Amazon, or in a store.

A really tiny number of people use more professional equipment at home.

The problem is, most IT professionals fall into one of the smaller two groups, so they get more friction than others, and that leads to them having more reluctance to roll out v6 at work, etc.

You have decades of networking experience but you are unable to get ipv6 to work, something that over 40% of internet users are using daily.

[1] https://www.google.com/intl/en/ipv6/statistics.html

I can get it to work just fine. It just doesn't work as well as IPv4 and I can't be bothered to figure out why.

I'm in that 40%. I use IPv6 on my phone whenever it's not in my house.

Debian would just not run due to apt repositories being borked if ipv6 was turned on.

My network is dual stack and all my VMs are Debian. No issues here.

anything more concrete?

i was struck by an issue in this area a few years ago and i think it was fixed by tuning gai.conf to prefer v4 because there were some repo servers that had broken v6

Which exact repo was that?

I seem to think that the primary UK mirror (http://ftp.uk.debian.org/) was problematic for v6 for a while? But these days the https://deb.debian.org/ mirror is really heavily pushed, and that one seems to work just fine.

edit: but this was quite a few years ago, from grepping my IRC logs, somewhere around 2016!

there are thousands of debian mirrors, not that far fetched that at least one of them has broken v6

> At some point a website I really want to access will require IPv6.

kek - i too am waiting