[kuschku]

In many countries, it’s common to have hundreds, even thousands of customers behind a single carrier-level CGNAT. This obviously prevents a lot of functionality from working.

In Germany, we’ve got enough IPv4s that every customer can have their own one, while e.g. in Asia CGNAT and IPv6 are long common.

[qwertox]

You won't get behind a CGNAT if you're connected via IPv4. As far as I know CGNAT is almost exclusively used for DS-Lite users.

[Dagger2]

There are sadly a ton of ISPs that do CGNAT on a v4-only service. Smaller or newer ISPs like WISPs often do it, or ISPs for apartment blocks or student accommodation, but it's hardly limited to those.

Germany in particular has a couple of large ISPs that give you a choice of either their new platform (DS-lite = v6 + CGNATed v4) or their old platform (v4-only). That's a choice made by those ISPs... and unfortunately it's one that causes a lot of people on those ISPs to end up blaming v6 for problems caused by CGNAT.

[qwertox]

Thanks for pointing this out.

[betaby]

Plenty of ISP in Europe do CGNAT without DS-Lite. Literally modems only gets IPv4 from 100.x.x.x range and that's it.