Create user for alternate port
Here is what I did:

CREATE USER 'myuser'@'localhost' IDENTIFIED BY 'mypass';
CREATE USER 'myuser'@'%' IDENTIFIED BY 'mypass';

GRANT ALL ON *.* TO 'myuser'@'localhost';
GRANT ALL ON *.* TO 'myuser'@'%';

In the php.ini:
mysql.default_port = &lt;private instance port&gt;    

In the forum settings, set database host to:
127.0.0.1