Comment # 1 on bug 1182831 from Stefan Dirsch

Hmm. Indeed looks like 15.0 and 15.1 repos are currently broken, but 15.1 is no
longer supported anyway since end of January 2021 ...
15.2 and TW repos are working. You need to be aware that directories on the
webserver are not browsable! Nevertheless they are working as repositories.  A
driver update for the repositories is triggered since end of last week. So
things will change soon anyway.