OHV VPS ports remain "closed" and can't be changed, why?

In case of your MySQL Daemon: It's set to listen to 127.0.0.1:3306. 127.0.0.1 is the loop back interface, and not reachable externally.

This is the default configuration of MySQL, and probably what you want unless you're aware that you have to change the configuration.

This is defined with the bind-address directive in the MySQL configuration file. Set it to 0.0.0.0 to make MySQL listen on all interfaces.

Note that this is probably not a good idea. It means that any vulnerability in MySQL may lead to a loss of database. To manage the DB, use SSH tunneling:

ssh -L 3306:127.0.0.1:3306 [email protected]

This will create a secure tunnel, using SSH, to transport packages from your PC to the remote server. Connect your MySQL client to localhost:3306, and enjoy.