Remote connections to MySQL/MariaDB database server fail when port 3306 is filtered by firewall

Symptoms

• When connecting to MySQL/MariaDB server, the operation fails.
• Remote MySQL connections are allowed in Plesk at Tools & Settings > Database Servers > localhost (next to MariaDB/MySQL).

Cause

Firewall blocks connections to MySQL server.

Resolution

Allow connections to port 3306 in firewall.

To allow connections in local firewall, instal and activate Plesk Firewall - it automatically opens all required ports.

When port 3306 is opened locally, but external connection still fails, contact sever network administrator / hosting provider to allow connections to port 3306.