When I entered domainname/phpmyadmin I can Connect MYSQL without any error.

But, I cannot connect MYSQL when I'm usıng connect.php file.
connect.php files include:
<?php
$servername = "domaınname";
$username = "root";
$password = "**";

// Create connection
$conn = mysqli_connect($servername, $username, $password);

// Check connection
if (!$conn) {
die("Connection failed: " . mysqliconnecterror());
}
echo "Connected successfully";*

and I'm writing this to firefox : domainname/connect.php
I get thıs error
Connection failed: Can't connect to MySQL server on 'domainName' (111)

thank you