Be advised that PHP >= 7 isn't supported yet.
I had to downgrade PHP back to 5.6.
PHP 5.3.6 or newer.
The mysqlnd_ms replication and load balancing plugin supports all PHP applications and all availablePHP MySQL extensions (mysqli, mysql, PDO_MYSQL). The PHP MySQL extension must be configured to use mysqlnd in order to be able to use the mysqlnd_ms plugin for mysqlnd.