Artefact download links missing after Teamcity update to 2021.2

I've installed Teamcity a few days ago to play around and test stuff and get used to it, and everything seems to work fine. But since yesterday, I cannot download artefacts anymore. They're created fine, they're there in the program data folder, they're even the overview page. Yet I cannot download them - earlier I had a small triangle next to the link, and clicking on a "innermost" link would download the file.

EDIT: it works directly on the server via http://localhost:8111, but not from other machines through https://public.domain.com

SOLUTION:

add

<system.web>
<httpRuntime requestPathInvalidCharacters="*,%,?,\,&amp;,&lt;,&gt;" />
<pages validateRequest="false" />
</system.web>

to the iis-site's web.config that does the reverse-proxying