I'm writing my first C# web application that connects to an XML based service. It requires that I present a certificate and feed the XML stream. It seems to authenticate properly but then it gives the following error: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 10.1.10.4:3128 The funny thing is that I'm not on a proxy or anything like that. I'm connecting directly to the internet. At one point I we did use a proxy that with internal NAT address. So my question is: Does Visual Studio have some sort of default proxy setting that I need to change? This IP is no longer used for anything, so I know that I don't need to use any proxy authentication code. using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Net; using System.Security.Cryptography.X509Certificates; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; namespace WebApplication1 { public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Uri requestURI = new Uri("*site omitted*"); //Create the Request Object HttpWebRequest pageRequest = (HttpWebRequest)WebRequest.Create(requestURI); //After installing the cert on the server export a client cert to the working directory as Deluxe.cer string certFile = "*certificate omitted*"; X509Certificate cert = X509Certificate.CreateFromCertFile(certFile); //Pull in your Data, if it is from an external xml as below or create an xml string with variables if a dynamic post is required. string xmlPath = "*XML omitted*"; System.Xml.XmlDocument passXML = new System.Xml.XmlDocument(); passXML.Load(xmlPath); //XML String with the data needed to pass string postData = passXML.OuterXml; //Set the Request Object parameters pageRequest.ContentType = "application/x-www-form-urlencoded"; pageRequest.Method = "POST"; pageRequest.AllowWriteStreamBuffering = false; pageRequest.AllowAutoRedirect = false; pageRequest.ClientCertificates.Add(cert); postData = "xml_data=" + Server.UrlEncode(postData); pageRequest.ContentLength = postData.Length; //Create the Post Stream Object System.IO.StreamWriter postStream = new System.IO.StreamWriter(pageRequest.GetRequestStream()); //Write the data to the post stream postStream.Write(postData); postStream.Flush(); postStream.Close(); //Set the Response Object HttpWebResponse postResponse = (HttpWebResponse)pageRequest.GetResponse();