Comment by codetrotter

It seems the other way around for the particular post you are linking.

This was posted to HN, then a bit picked it up from RSS and cross posted the same link to r/hackernews on Reddit (your Reddit link).

Then the repo.aalto.fi site was temporarily hugged by too much traffic.

Then someone reuploaded the PDF to this other tiiny site. Then the link on HN was changed to that. Then the file on the tiiny site disappeared.

Regardless, thanks for the link. The repo.aalto.fi link currently works for me. Probably because it’s getting much less traffic now.