It's the site you find when you search for dns4eu.

$ whois AS60068 [...] organisation: ORG-DL201-RIPE org-name: Datacamp Limited country: GB org-type: LIR address: 207 Regent Street address: W1B 3HH address: London [...]

In the era of relatively complicated company ownership structures (especially in a capital heavy business such as Datacamp), the company on the whois does have the same level of meaning as you seem to expect it to.

207 Regent Street, it's a relatively well known virtual office type address, I would be shocked to learn that there were any datacamp employees at that address)

Virtual office addresses don't help to make it better.

Run your own resolver. It's not that hard.

Sure thing, but essentially it would be another thing that we have to make sure that it is protected and performant. At the time of building a startup, that’s still an item we are leaving someone else to manage.

It's simple to setup a resolver, really. Basically just "apt install unbound" and you have a resolver ready.

the only thing you might have to adjust is the access control

https://www.linuxbabe.com/ubuntu/set-up-unbound-dns-resolver...

      access-control: 10.0.0.0/8 allow
      access-control: 127.0.0.1/24 allow
      access-control: 2001:DB8::/64 allow

That's the policy. In real life I only found AS60068.

It may brake SLAAC. OpenBSD implements autoconfiguration for non /64 prefixes (IIRC)

> I mean even if there is no "Happy Eyeballs", it would still work for end users, > no?

No browsers and other clients prefer IPv6 and there would be a rather long timeout till the client falls back and tries IPv4. If it falls back.

> So why would it work sometimes if IPv6 is consistently broken and IPv4 is not? > (I'm not saying it won't happen; just that it shouldn't be "caused by HE" -- HE > literally is the solution to this issue in general as the author said > themselves!)

IPv6 wasn't broken. For HE, an HTTP 403 is a valid connection. TCP handshake works, IPv6 works.

I had another case where the TCP handshake worked, and the browser decided to use IPv6 is good, but then came the TLS handshake, and it failed because PMTUD (Path MTU Discovery) was broken.