[ddtaylor]

This is not how this works anymore. The system that is behaving this way must be relatively old at this point since almost all modern Debian based distros use the "mirror://" URI syntax now that automatically falls back to another mirror if one fails.

[pxc]

I don't think a clean Debian stable install uses that today.

But even so, at least the mirrorlist.txt file that appears in the mirror:// URI must be available for it to work, right?

[ddtaylor]

You are correct. While it's supported and part of the APT version in Debian, they don't make much use of it themselves, whereas most downstream distros are making use of it (eg. Ubuntu)

https://manpages.debian.org/bullseye/apt/apt-transport-mirro...

You can still use it in vanilla Debian, but they don't make their mirror list available easily in the correct format, so you would have to basically curl + awk the URLs into a text file and use that.

My guess is that Debian itself probably sees less than 1% of the traffic on their mirrors compared to Ubuntu and they haven't been as motivated to make this change.