How do I send message on networkstream with multithread ?

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C#

threads

stream

sockets

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I have a WinForms application C#. In here, I used TcpClient/Socket and NetworkStream. I have created multiple thread to handle sending/receiving from client/server. Assuming I'm forced to use TcpClient/Socket, I won't use other libraries or third-party.

I can initiate multiple threads, and manage server/client connection in each thread. At the beginning, when I initialize (press start button), can send/receive data between client/server.

For example: I have 2 servers/ports, they will listening connections from the client side.
Server A: 192.168.10.1/5555
Server B: 192.168.10.1/6666

After initialization, I received 2 connections from client to server. They're connected normal between client/server in each Thread. And some data send/receive at the beginning working well also, assuming server sending "Hello", and client reply "Ok. I'm fine", this way happened on separate threads, not overlapping each other.
192.168.10.1/5555 - 10.10.10.1/34546
192.168.10.1/6666 - 10.10.10.1/54632

After that, I proceeded to manually send data from server A 192.168.10.1/5555 to client 10.10.10.1/34546. For server A works normally, the client 10.10.10.1/34546 can receive data. But when I send information from server B 192.168.10.1/6666 to client 10.10.10.1/54632, It doesn't work although before that it received normal data at initialization.

What I have tried:

public class Conn
{
    private TcpListener listener;
    private Socket socket;
    private NetworkStream stream;

    public TcpListener CListener
    {
        get { return listener; }
        set { listener = value; }
    }
    public Socket CSocket
    {
        get { return socket; }
        set { socket = value; }
    }
    public NetworkStream CStream
    {
        get { return stream; }
        set { stream = value; }
    }
}
private List<Conn> conn_list = null;
private async void _start_multi(Conn connection, TcpListener listener_multi, Socket socket_multi, NetworkStream stream_multi, string _ip, int _port)
{
    try
    {
        listener_multi = new TcpListener(IPAddress.Parse(_ip), _port);
        connection.CListener = listener_multi; //create listener
        listener_multi.Start();
        socket_multi = listener_multi.AcceptSocket();
        connection.CSocket = socket_multi; //create socket
        socket_multi.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.KeepAlive, true);
        socket_multi.SendTimeout = 180000;
        socket_multi.ReceiveTimeout = 180000;
        stream_multi = new NetworkStream(socket_multi);
        connection.CStream = stream_multi; //create stream
        while (true)
        {
            byte[] myReadBuffer = new byte[1024 * 5];
            int numberOfBytesRead = 0;
        rec_continute:
            numberOfBytesRead = stream_multi.Read(myReadBuffer, 0, myReadBuffer.Length);
            byte[] bytes_real = new byte[numberOfBytesRead];
            Buffer.BlockCopy(myReadBuffer, 0, bytes_real, 0, numberOfBytesRead);
            if (bytes_real.Length != 0)
            {
                byte[] msg_temp = Encoding.ASCII.GetBytes(Encoding.ASCII.GetString("HELLO"));
                stream_multi.Write(msg_temp, 0, msg_temp.Length);
                stream_multi.Flush();
                goto rec_continute;
            }
            if (bytes_real.Length == 0)
            {
                break;
            }
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show("Warning" + ex.Message);
    }
}
private void bt_turnon_multi_Click(object sender, EventArgs e)
{
        dgv_multi_ip.Rows.Add("192.168.10.1", "5555");
        dgv_multi_ip.Rows.Add("192.168.10.1", "6666");
        for (int i = 0; i < dgv_multi_ip.Rows.Count; i++)
        {
            var ip = dgv_multi_ip.Rows[i].Cells[0].Value.ToString();
            var port = int.Parse(dgv_multi_ip.Rows[i].Cells[1].Value.ToString());
            var connection = conn_list[i];
            TcpListener listener_multi = null;
            Socket socket_multi = null;
            NetworkStream stream_multi = null;
            System.Threading.Thread thread = new System.Threading.Thread(() =>
            {
                _start_multi(connection, listener_multi, socket_multi, stream_multi, ip, port);
            });
            thread.Start();
        }
}
private async Task send_msg_multi(Conn connection)
{
    byte[] messageBytes = Encoding.ASCII.GetBytes(Encoding.ASCII.GetString("ARE YOU OK?"));
    try
    {
        connection.CStream.Write(messageBytes, 0, messageBytes.Length);
        connection.CStream.Flush();
        return;
    }
    catch (Exception ex)
    {
        MessageBox.Show("Can not send msg" + ex.Message);
    }
}
private async void bt_send_multi_Click(object sender, EventArgs e)
{
                for (int i = 0; i < conn_list.Count; i++)
                {
                        await send_msg_multi(conn_list[i]);
                }
}