I have the following setup on my server: Centos version 7.4 Webmin version 1.872 Virtualmin version 6.02 Nginx with rh-php56-php-fpm installed and everything is working great!
I found a few issues though after installing a 2nd virtual server.
Under 'Server configuration -> Php options' on a 2nd server, it's missing the 'Default HTML directory' and only has blank field input for PHP version selection.
On my 1st virtual server setup, I was able to easily update 'Default HTML directory' Php version to 5.6 without breaking a sweat.
I'm not sure why 'Default HTML directory' no longer appears on a 2nd domain virtual server or thereafter.
It causes problems when installing a script such as Phpmyadmin (4.7.7) which requires Php 5.6 and above I believe.
I even tried the previous version of Phpmyadmin (4.4.15) and surprisingly it also fails with the following message:
"Failed to install script : Could not find PHP version for ..."
Therefore it's not possible to install phpmyadmin on the 2nd virtual server setup and on.