One interesting thing is the asymmetry making it slower for all those backend services to move, as opposed to, say, a brand new ISP. Cloud/hosting services onl

One interesting thing is the asymmetry making it slower for all those backend services to move, as opposed to, say, a brand new ISP. Cloud/hosting services only need one IPv4 per machine, making them relatively cheap, and easy to include in pricing. ISPs need one IPv4 per customer, or resort to CGNAT or IPv4-sharing. This often means that customers might have better IPv6 than IPv4 performance. All of this does not apply to oldest ISPs that all have a war-chest of IPv4 they got for cheap (free). Where I'm getting at is that the usecase you're testing is basically worst-case scenario. Fun that Hetzner does not even have AAAA records for their API. Do they have at least RFC1918 (private) IPv4 addresses ?