hello i have encountered this error and dont know how to fix it. my password and all the stuff i use are correct but somehow this still shows up

This is the code im using for connecting to the server:

<?php

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

define('DB_SERVER', 'servername');
define('DB_USERNAME', 'myuser');
define('DB_PASSWORD', 'veryverysecretpassword');
define('DB_NAME', 'adress');

$link = mysqli_connect(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_NAME);

if($link === false){
    die("ERROR: Could not connect. " . mysqli_connect_error());
} else {
    echo "Connection successful.";
}
?>

i tried to change the serer name and the table name but all that doesnt work