Can't connect to MYSQL server on ... (13)

[kenneth watanabe]

When I run my PHP script, I get the following error:
Can't connect to MYSQL server on ... (13)

Below is the PHP code:
<?php
$hostnameGS = "170.140.xxx.xxx";
$databaseGS = "tfbs_db";
$usernameGS = "kawatan";
$passwordGS = "xxxxxx";
$connGS = mysqli_connect($hostnameGS, $usernameGS, $passwordGS,$databaseGS) or trigger_error(mysql_error(),E_USER_ERROR);

$sql_cmd = "select matrix_id,matrix_count from matrix_counts where matrix_id = 'V$ZNF100_01'";
$sql = mysqli_query($connGS,$sql_cmd) or die(mysql_error());
$row = mysqli_fetch_assoc($sql);
?>

The PHP script is running on a different server than the database.
I tried turning off SELINUX on the database server but it did not help.

Any help would be appreciated.
Ken