exe Вы выходите из программ путаницы, варьируются по скорости?

 public  SendNotice(int deviceType, string deviceToken, string message, int badge, int status, string sound)
    {
        AndroidFCMPushNotificationStatus result = new AndroidFCMPushNotificationStatus();
        try
        {
            result.Successful = false;
            result.Error = null;
            var value = message;
            WebRequest tRequest = WebRequest.Create("https://fcm.googleapis.com/fcm/send");
            tRequest.Method = "post";
            tRequest.ContentType = "application/json";
            var serializer = new JavaScriptSerializer();
            var json = "";
            tRequest.Headers.Add(string.Format("Authorization: key={0}", "AA******"));
            tRequest.Headers.Add(string.Format("Sender: id={0}", "11********"));
           if (DeviceType == 2)
            {
                var body = new
                  {
                      to = deviceToken,
                      data = new
                      {
                          custom_notification = new
                            {
                                title = "Notification",
                                body = message,
                                sound = "default",
                                priority = "high",
                                show_in_foreground = true,
                                targetScreen = notificationType,//"detail",
                                                                },
                      },

                      priority = 10
                  };

                json = serializer.Serialize(body);
            }
            else
            {
                var body = new
                {
                    to = deviceToken,
                    content_available = true,
                    notification = new
                    {
                        title = "Notification",
                        body = message,
                        sound = "default",
                        show_in_foreground = true,
                    },
                    data = new
                    {
                        targetScreen = notificationType,
                        id = 0,
                    },
                    priority = 10
                };
                json = serializer.Serialize(body);
            }

            Byte[] byteArray = Encoding.UTF8.GetBytes(json);

            tRequest.ContentLength = byteArray.Length;

            using (Stream dataStream = tRequest.GetRequestStream())
            {
                dataStream.Write(byteArray, 0, byteArray.Length);

                using (WebResponse tResponse = tRequest.GetResponse())
                {
                    using (Stream dataStreamResponse = tResponse.GetResponseStream())
                    {
                        using (StreamReader tReader = new StreamReader(dataStreamResponse))
                        {
                            String sResponseFromServer = tReader.ReadToEnd();
                            result.Response = sResponseFromServer;
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            result.Successful = false;
            result.Response = null;
            result.Error = ex;
        }
}