The operation has timed out ~ System.Net.WebException: The operation has timed out

The operation has timed out ~ System.Net.WebException: The operation has timed out at System.Net.HttpWebRequest.GetRequestStream(TransportContext& context) at System.Net.HttpWebRequest.GetRequestStream()

doing a load testing of http server with multiple requests per second. after few hundred successful requests and responses, new request get stuck and after the timeout value is achieved(timeout = 30 second) request timeout exception is thrown. all the solutions i found was regarding closing the stream properly which I hope I am doing. Any help on resolving the timeout problem would be appreciated. thanks.

  using (System.IO.Stream requestStream = client.GetRequestStream())
  {
                    requestStream.Write(content, 0, content.Length);

                    requestStream.Close();

                }