Иногда я получаю следующую ошибку, когда я делал HttpWebRequest для WebService. Я тоже скопировал свой код.
System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it 127.0.0.1:80 at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress) at System.Net.Sockets.Socket.InternalConnect(EndPoint remoteEP) at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception) --- End of inner exception stack trace --- at System.Net.HttpWebRequest.GetRequestStream()
ServicePointManager.CertificatePolicy = new TrustAllCertificatePolicy();
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.PreAuthenticate = true;
request.Credentials = networkCredential(sla);
request.Method = WebRequestMethods.Http.Post;
request.ContentType = "application/x-www-form-urlencoded";
request.Timeout = v_Timeout * 1000;
if (url.IndexOf("asmx") > 0 && parStartIndex > 0)
{
    AppHelper.Logger.Append("#############" + sla.ServiceName);
    using (StreamWriter reqWriter = new StreamWriter(request.GetRequestStream()))
    {                        
        while (true)
        {
            int index01 = parList.Length;
            int index02 = parList.IndexOf("=");
            if (parList.IndexOf("&") > 0)
                index01 = parList.IndexOf("&");
            string parName = parList.Substring(0, index02);
            string parValue = parList.Substring(index02 + 1, index01 - index02 - 1);
            reqWriter.Write("{0}={1}", HttpUtility.UrlEncode(parName), HttpUtility.UrlEncode(parValue));
             if (index01 == parList.Length)
                 break;
             reqWriter.Write("&");
             parList = parList.Substring(index01 + 1);
         }
     }
 }
 else
 {
     request.ContentLength = 0;
 }
 response = (HttpWebResponse)request.GetResponse();


