PHP Socket connection - Connection Refused

Question

I have a simple PHP script to connect to a remote VB.NET server application on port 9999. I can telnet (on port 9999) from the web to External IP address & port but I can not get the script to connect - keep getting Connection Refused. Port 9999 is open & Sockets is enabled in PHP.

<?php
$host="<IP Address>" ;
$port=9999;
$timeout=30;
$sk=fsockopen($host,$port,$errnum,$errstr,$timeout) ;
if (!is_resource($sk)) {
    exit("connection fail x: ".$errnum." ".$errstr) ;
} else {
    fputs($sk, "hello world") ;
    $dati="" ;
    while (!feof($sk)) {
        $dati.= fgets ($sk, 1024);
    }
}
fclose($sk) ;
echo($dati) ;
?>

Help - What am I doing wrong?

Answer 1

This works when I test it locally with netcat listening on port 9999... so, nothing. The problem is either in the middle or on the other side.