How to create a subdomain based WordPress multisite on the Virtualmin control panel

Here is the quick guide on how to create WordPress multi-site if you’re hosting it on Virtualmin. This example is for domain based multi-site, versus subdirectory-based multi-site.

Create the main domain

Use Install Script to install WordPress

Add the following one liner to wp-config.php:

define( 'WP_ALLOW_MULTISITE', true );

Now got to Tools -> Network Setup and choose your sub-site settings.
Choose domain based, not subdirectory based

Go back to wp-admin and add this:

define('WP_ALLOW_MULTISITE', true ); 
define('SUBDOMAIN_INSTALL', true); 
define('DOMAIN_CURRENT_SITE', 'example.com');
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1); 
define('BLOG_ID_CURRENT_SITE', 1);

Create aliases in Virtualmin and re-request SSL for the entire domains and it’s aliases.

Done!