Did you check whether this behaviour still exists in current master? We've removed gitno_extract_url_parts due to some refactorings in c6ab183 (net: rename gitno_connection_data to git_net_url, 2019-03-11), and we're not passing any default ports anymore. I'd thus expect that this has been implicitly fixed already.

I confirm. The issue only exists in 0.28.3.

Still, because as of latest libgit2sharp is using 0.28.4, the issue affects a PR that would allow libgit2sharp to detect proxy settings libgit2/libgit2sharp#1708 . I'll move the discussion there

Thanks a lot for confirming! Normally I'd consider backporting, but backporting this particular season doesn't seem feasible to me as there's too many things that've been changed. It's a bit unfortunate, but yeah. We're prorably going to release v0.99 soon-ish anyway, at which point libgit2sharp could upgrade to our newer release.