How to use http post with proxy support in c# and multipart form data upload method
If the web request works fine in your localhost with default proxy and not working in your web server, then you have to set your company's approved proxy and also whitelist the URL you are connecting to from your web application in the web server.
You can mention the proxy settings either in web.config or in code.
(or)
HttpWebRequest wr = (HttpWebRequest)WebRequest.Create("URL");
wr.Proxy = new WebProxy("companyProxy",Portnumber);
wr.Method = "POST";