Зависание программы при отправке POST-запроса

    HttpWebRequest myRequest = (HttpWebRequest)HttpWebRequest.Create(url + adr);
    HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();
    StreamReader sr = new StreamReader(myResponse.GetResponseStream(), Encoding.GetEncoding("utf-8"));
    stri = sr.ReadToEnd();
    sr.Close();
           
    return stri;

            WebRequest req = WebRequest.Create("http://h60257.srv5.test-hf.ru/"+ myuser + "/chat");
            req.Method = "POST";
            req.Timeout = 20000;
            req.ContentType = "application/x-www-form-urlencoded";
            byte[] sentData = Encoding.UTF8.GetBytes("text=SkoT|"+addtext_chat.Text);
            req.ContentLength = sentData.Length;
            Stream sendStream = req.GetRequestStream();
            sendStream.Write(sentData, 0, sentData.Length);
            sendStream.Close();
            addtext_chat.Clear();
            ClearChater.Start();
            GetMes();

        public static void SendPOST(string urladr, string textvalue)
        {
           
            using (WebClient webClient = new WebClient())
            {
                byte[] postData = Encoding.UTF8.GetBytes(textvalue);
                webClient.Headers[HttpRequestHeader.Accept] = "text/html, application/xhtml+xml, */*";
                webClient.Headers[HttpRequestHeader.AcceptLanguage] = "ru-RU";
                webClient.Headers[HttpRequestHeader.UserAgent] = "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)";
                webClient.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
                webClient.UploadData(urladr, postData);
            }
            
        }
        public static string GetString(string adr)
        {
          WebClient web = new WebClient();
          web.Encoding = Encoding.UTF8;
          var str = web.DownloadString(url + adr);
          return str;
        }