I'm glad manually removing the partially-downloaded fonts fixed the issue for you.
A bug about partially-downloaded fonts preventing the rest of the download is currently being fixed in bug 1657567. However, the error that is thrown out in that case (Content-Range error) is not the same as the one you report in your comment 80 (Protocol "http" not supported or disabled in libcurl). There would be ground for a separate bug report regarding your issue, I think.
I'm glad manually removing the partially- downloaded fonts fixed the issue for you.
A bug about partially- downloaded fonts preventing the rest of the download is currently being fixed in bug 1657567. However, the error that is thrown out in that case (Content-Range error) is not the same as the one you report in your comment 80 (Protocol "http" not supported or disabled in libcurl). There would be ground for a separate bug report regarding your issue, I think.