just wondering here, but can the urpmi command work on anything else? like installing a package from the default repositories? because what usually worked back when I used mandriva was to switch between mirrors, although as you say, this one seems to be online.
medium "Core Release" is up-to-date
http://distro.ibiblio.org/mageia/distrib/5/x86_64/media/core/updates/media_info/20170129-223032-synthesis.hdlist.cz
updated medium "Core Updates"
medium "Core 32bit Release" is up-to-date
http://distro.ibiblio.org/mageia/distrib/5/i586/media/core/updates/media_info/20170129-222653-synthesis.hdlist.cz
updated medium "Core 32bit Updates"