WP_FAIL2BAN_BLOCK_USERNAME_LOGIN

Force login with email address/prevent login with username.

Default setting: disabled

Forces users to log in using their email address instead of their username. This provides an alternative to blocking user enumeration when using themes with author profile pages.

Example: Force email login

/**
 * Force login with email address/prevent login with username.
 */
define('WP_FAIL2BAN_BLOCK_USERNAME_LOGIN', true);

Important

You should define this in wp-config.php even if you are using the Premium flavour of WPf2b.