WebClient from Asp.net gives "an existing connection was forcibly closed by the remote host" Error

I am trying to publish an asterisk in our window to parse the list of phones

from a console app this works:

 class Program
  {
    static void Main(string[] args)
    {


        Console.WriteLine( HttpPost());
        System.Threading.Thread.Sleep(10000);
    }

    public static string HttpPost()
    {
        var URI = @"http://sip.ligmarine.com/admin/config.php?quietmode=on&type=tool&display=printextensions";
        var Parameters = "display=printextensions&quietmode=on&type=tool&core=core&featurecodeadmin=featurecodeadmin&paging=paging";
        var retVal = "";
        WebClient wc = new WebClient();

        wc.Headers.Add("Authorization", "Basic " + Convert.ToBase64String(Encoding.ASCII.GetBytes("maint:password")));
        wc.Headers.Add("referer", @"http://sip.ligmarine.com/admin/config.php?type=tool&display=printextensions");
        wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded");

        retVal = Convert.ToBase64String(Encoding.ASCII.GetBytes("maint:password"));
        //Console.Write("Resulting Request Headers: ");
        //Console.WriteLine(wc.Headers.ToString());
        byte[] byteArray = Encoding.ASCII.GetBytes(Parameters);
        //Console.WriteLine("Uploading to {0} ...", URI);
        // Upload the input string using the HTTP 1.0 POST method.
        byte[] responseArray = wc.UploadData(URI, "POST", byteArray);
       // Console.WriteLine("\nResponse received was {0}", );

        retVal = Encoding.ASCII.GetString(responseArray);

        return retVal;
    }
}

      

        
        
        
      

    

from our IIS6 Hosted ASP.NET page I get

an existing connection was forcibly closed by the remote host Description: An unhandled exception occurred during the execution of the current website request. Check out the stack trace for more information on the error and where it originated from the code.

 Exception Details: System.Net.Sockets.SocketException: An existing connection was      forcibly closed by the remote host

 Source Error:

 Line 37:         //Console.WriteLine("Uploading to {0} ...", URI);
 Line 38:         // Upload the input string using the HTTP 1.0 POST method.
 Line 39:         byte[] responseArray = wc.UploadData(URI, "POST", byteArray);
 Line 40:         // Console.WriteLine("\nResponse received was {0}", );
 Line 41: 

      

        
        
        
      

    

The HttpPost method is exactly identical to page load:

protected void Page_Load(object sender, EventArgs e)
{

    var ret = HttpPost();
    Response.Write(ret);
}