The operation has timed out

System.Net.WebException: The operation has timed out
   at System.Net.WebClient.DownloadDataInternal(Uri address, WebRequest& request)
   at System.Net.WebClient.DownloadData(Uri address)

System.Net.WebClient myClient = new WebClient();
            myClient.Credentials = adminCredentials;
            byte[] requestHTML;
            requestHTML = myClient.DownloadData(fileUrl);
            myPageHTML = utf8.GetString(requestHTML);
            myClient.Dispose();