Cloudflare and fail2ban
For sites behind Cloudflare the use of wp-fail2ban plugin could cause the site to be made unavailable to all if a block of the Cloudflare servers was triggered by a series of failed logins.
The answer is to create a script to fetch the latest list of Cloudflare IP addresses and add then to the wp-config.php
file, see WP_FAIL2BAN_PROXIES.