Connection Refused on connecting to a remote server

I’m new to web development. I bought a server on DigitalOcean, created a droplet and installed LAMP. I have a simple PHP script to connect to MySQL. Here’s my PHP script(conn.php)

<?php $servername = “xxx.xx.xx.xxx”; $username = “root”; $password = “my_password”; try { $conn = new PDO(“mysql:host=$servername;dbname=mysql”, $username, $password); // set the PDO error mode to exception $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); echo “Connected successfully”; }catch(PDOException $e) { echo "Connection failed: " . $e->getMessage(); } ?> Now, when I try to run on my browser “xxx.xx.xx.xxx/conn.php”, it’s printing

Connection failed: SQLSTATE[HY000] [2002] Connection refused