C# socket issue in receiving images

i did create socket application to send and receive images over internet

i did test the application locally and on vmware , it did works fine

also test it on some devices over internet also worked fine

but there is other devices that the Server application receive only small amount of the sent data

here is an image of the server image

and this is the server code

while(true)
        {
            Socket socket = listener.AcceptSocket();
            label4.Text = "Connected";
            byte[] image = new byte[99999999];
            int offset = -1;
            int ite = 0;
            while (true)
            {
                
                byte[] data = new byte[1024];
                int count = socket.Receive(data);
                if (count > 0)
                {
                    String txt = Encoding.ASCII.GetString(data, 0, count);

                    if (txt.Contains("hello"))
                    {
                        label8.Text = txt;
                        continue;
                    }
                    if (!txt.Contains("end"))
                    {
                        ite += 1;
                        label7.Text = ite.ToString();
                        label12.Text = offset.ToString();
                        for (int i = 0; i <= count - 1; i++)
                        {
                            offset += 1;
                            image[offset] = data[i];                                
                        }
                        try
                        {
                            MemoryStream stream = new MemoryStream(image, 0, offset);
                            Image x = Image.FromStream(stream);
                            pictureBox1.Image = x;
                        }
                        catch (Exception ex)
                        {

                        }
                    }
                    else
                    {
                        label7.Text = ite.ToString();
                        ite = 0;
                        label5.Text = label2.Text;
                        label2.Text = offset.ToString();
                        MemoryStream stream = new MemoryStream(image, 0, offset);
                        Image x = Image.FromStream(stream);
                        pictureBox1.Image = x;

                        image = new byte[99999999];
                        offset = -1;
                        break;

                    }


                }
            }
        }

and this is the client code

 while (true)
            {
                TcpClient client = new TcpClient(ip, port);
                NetworkStream stream = client.GetStream();
                byte[] data = Capture();
                int dataSize = 1024;
                int offset = 0;
                byte[] start = ASCIIEncoding.ASCII.GetBytes("hello " + data.Length.ToString());                    
                stream.Write(start, 0, start.Length);                
                while (offset < data.Length)
                {
                    int sum = offset + dataSize;
                    if (sum > data.Length)
                    {
                        dataSize = data.Length - offset;
                    }
                    stream.Write(data, offset, dataSize);

                    offset += dataSize;
                }
                Thread.Sleep(1000);
                byte[] end = ASCIIEncoding.ASCII.GetBytes("end");
                stream.Write(end, 0, end.Length);

                client.Close();
                Thread.Sleep(interval);
                Console.WriteLine("iter=" + iteration.ToString());
            }