In order to conserve the limited bandwidth available, ISO images are not downloadable from mirror.centos.org

http://mirror.cs.vt.edu/pub/CentOS/8.4.2105/isos/x86_64/
http://mirror.vcu.edu/pub/gnu_linux/centos/8.4.2105/isos/x86_64/
http://mirror.cogentco.com/pub/linux/centos/8.4.2105/isos/x86_64/
http://mirror.centos.iad1.serverforge.org/8.4.2105/isos/x86_64/
http://mirrors.advancedhosters.com/centos/8.4.2105/isos/x86_64/
http://mirror.vtti.vt.edu/centos/8.4.2105/isos/x86_64/
http://us.mirror.nsec.pt/centos/8.4.2105/isos/x86_64/
http://mirror.ash.fastserv.com/centos/8.4.2105/isos/x86_64/

http://centos.mirrors.tds.net/pub/linux/centos/8.4.2105/isos/x86_64/
http://la.mirrors.clouvider.net/CentOS/8.4.2105/isos/x86_64/
http://mirror.steadfastnet.com/centos/8.4.2105/isos/x86_64/
http://mirrors.usinternet.com/centos/8.4.2105/isos/x86_64/
http://mirror.san.fastserv.com/pub/linux/centos/8.4.2105/isos/x86_64/
http://mirrors.ocf.berkeley.edu/centos/8.4.2105/isos/x86_64/
http://mirror.nodesdirect.com/centos/8.4.2105/isos/x86_64/
http://mirror.ancl.hawaii.edu/linux/centos/8.4.2105/isos/x86_64/
http://repos.lax.quadranet.com/centos/8.4.2105/isos/x86_64/
http://mirror.cs.pitt.edu/centos/8.4.2105/isos/x86_64/
http://mirror.sfo12.us.leaseweb.net/centos/8.4.2105/isos/x86_64/
http://mirrors.tripadvisor.com/centos/8.4.2105/isos/x86_64/
http://mirror.es.its.nyu.edu/centos/8.4.2105/isos/x86_64/
http://mirror.dal.nexril.net/centos/8.4.2105/isos/x86_64/
http://mirror.netdepot.com/centos/8.4.2105/isos/x86_64/
http://mirror.centos.lax1.serverforge.org/8.4.2105/isos/x86_64/
http://mirror.teklinks.com/centos/8.4.2105/isos/x86_64/
http://mirrors.wcupa.edu/centos/8.4.2105/isos/x86_64/
http://mirror.umd.edu/centos/8.4.2105/isos/x86_64/
http://mirror.pit.teraswitch.com/centos/8.4.2105/isos/x86_64/
http://mirror.chpc.utah.edu/pub/centos/8.4.2105/isos/x86_64/
http://repo1.dal.innoscale.net/centos/8.4.2105/isos/x86_64/
+ others, see the full list of mirrors: https://www.centos.org/download/mirrors/

Mirrors verified Wed Oct 27 09:55:42 2021 UTC

You can also download the ISO images using bittorrent, a peer-to-peer file sharing protocol. The .torrent files can be found from CentOS mirrors. Various bittorrent clients are available, including (in no particular order of preference): utorrent, vuze (Azureus), BitTorrent, Deluge, ctorrent, ktorrent, rtorrent and transmission. Packaged copies of various torrent clients for CentOS can be found in the repositories listed in the following wiki article: https://wiki.centos.org/AdditionalResources/Repositories