On the page https://www.freebsd.org/doc/handbook/introduction.html is a link in the footer to download the documentation "All FreeBSD documents are available for download at http://ftp.FreeBSD.org/pub/FreeBSD/doc/ " The link http://ftp.FreeBSD.org/pub/FreeBSD/doc/ works fine. However, if you replace it with an HTTPS link https://ftp.FreeBSD.org/pub/FreeBSD/doc/ you will be redirect to https://download.freebsd.org/pub/FreeBSD/doc/ and get a HTTP status 404 I'm not sure if the redirect from "ftp.freebsd.org" to "download.freebsd.org" is by intention. But if we do this, then the redirect link should be apparently https://download.freebsd.org/ftp/doc/
IIRC the redirect from ftp to download came when we realized that 'ftp' is a silly name when no one is using the FTP protocol to download things, and "download.freebsd.org" reads almost like a direction to "download FreeBSD", which has some advertising value. So, download became the authoritative name but the ftp name was retained for compatibility. I would support changing the link to be to https://download.freebsd.org/ftp/doc/
I agree that "download" is a better hostname than "ftp", and that we should fix the links in our documentation.
A commit references this bug: Author: wosch Date: Sun Oct 1 12:05:26 UTC 2017 New revision: 51014 URL: https://svnweb.freebsd.org/changeset/doc/51014 Log: change download links from ftp to download.freebsd.org PR: 222678 Changes: head/ko_KR.UTF-8/share/xml/freebsd-xhtml.xsl head/ru_RU.KOI8-R/share/xml/freebsd-xhtml.xsl head/share/xml/freebsd-xhtml-common.xsl
A commit references this bug: Author: wosch Date: Sun Oct 1 12:10:32 UTC 2017 New revision: 51015 URL: https://svnweb.freebsd.org/changeset/doc/51015 Log: change download links from ftp to download.freebsd.org PR: 222678 Changes: head/en_US.ISO8859-1/articles/mailing-list-faq/article.xml
A commit references this bug: Author: wosch Date: Sun Oct 1 12:11:14 UTC 2017 New revision: 51016 URL: https://svnweb.freebsd.org/changeset/doc/51016 Log: change download links from ftp to download.freebsd.org PR: 222678 Changes: head/en_US.ISO8859-1/books/arch-handbook/book.xml head/en_US.ISO8859-1/books/developers-handbook/book.xml head/en_US.ISO8859-1/books/faq/book.xml head/en_US.ISO8859-1/books/handbook/book.xml
The other reason was that Safari on OS X, connects on port 21 no matter what, even if the URL is https://ftp.freebsd.org/ It was a workaround for that rather silly bug that prevented people clicking download links.