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Here is my updated code which is used to established a multiple connection and send data to device/client from server but my server does not receive a data from client, how to solve this issue please help me to solve this issue.

What I have tried:

Below code is my updated code from single connection to multiple connection. When I select a client from the list of connected device my server send the data to client easily but my server does not receive a data from client.

This section of code is established a multiple connection with device
private void btnstart_Click(object sender, EventArgs e)

              string Systemip = getlocalip();
              txtinfo.Text = "Server IP:" + Systemip + Environment.NewLine;
              var portno = Int32.Parse("8010");

              String a = "";

              IPAddress ip = IPAddress.Parse(Systemip);
              server = new TcpListener(ip, portno);

             //here environment.newline means, display msg to next line.
              txtinfo.AppendText("Server started waiting for client.............." + Environment.NewLine);
          counter = 0;
          f = new Form1();
          Thread newone = new Thread(loop);

      public delegate void messageone();
      public void mess()

          richtxtbddata.AppendText(counter + "clien connected" + Environment.NewLine);
          richtxtbddata.AppendText("The client is from IP address: " + ((IPEndPoint)socketforclient.RemoteEndPoint).Address.ToString() + Environment.NewLine);
      //    iplist.Items.Add(((IPEndPoint)socketforclient.RemoteEndPoint).Address.ToString());
          listBox1.Items.Add(counter);         //add this (((IPEndPoint)clientSocket.RemoteEndPoint).Address.ToString()); on the place of counter

      public void loop(object obj)
          connectobj = new List<Multipleconnect>();

          while (true)

              socketforclient = server.AcceptSocket();
             // ns = new NetworkStream(socketforclient);
              connectobj.Add(new Multipleconnect
                  objectno = counter,
                  Skt = socketforclient,
                  nstream = new NetworkStream(socketforclient),
                  ip = ((IPEndPoint)socketforclient.RemoteEndPoint).Address.ToString()

              //Box.AppendText(counter + "Client connected");
              richtxtbddata.Invoke(new messageone(mess));
              Thread UserThread = new Thread(new ThreadStart(() => f.User(socketforclient)));

      public void User(Socket client)
          while (true)
                  byte[] msg = new byte[1024];
                  int size = client.Receive(msg);
                  client.Send(msg, 0, size, SocketFlags.None);
              catch (Exception ex)
                  txtinfo.Text = "Divice Disconnected";



This code for sending and receiving data. server send data to client successfully but this server does not receive a data from client.
private void btnsend_Click(object sender, EventArgs e)

       isNew = true;

           if (servermsg.Text != "") {

               ns = new NetworkStream(socketforclient);
               StreamWriter writer = new StreamWriter(ns);

               writer.WriteLine(servermsg.Text + Environment.NewLine);
               txtinfo.AppendText("Server:" + servermsg.Text + Environment.NewLine);

           ns = new NetworkStream(socketforclient);
           StreamReader sr = new StreamReader(ns);
           string myCompleteMessage = string.Empty;

           if (ns.DataAvailable)
               myReadBuffer = new byte[2048];
               datafinal = new double[1];

               myCompleteMessage = Encoding.ASCII.GetString(myReadBuffer, 0, readbytes);



           if (myCompleteMessage != "")
              txtinfo.AppendText("Client:" + myCompleteMessage + Environment.NewLine + Environment.NewLine);

Updated 15-Apr-21 20:23pm

1 solution

You were given some suggestions over a week ago at How to connect multiple devices with server using TCP?[^].
Share this answer
Member 14743579 15-Apr-21 6:06am    
Actually my code established a connection with multiple devices/clients and after when i select a device from a list of connected device my server send a messages to client perfectly but my server is not able to read a data or message from client.
Richard MacCutchan 15-Apr-21 6:07am    
Why not? If you can send data to a client you should be able to receive as well.
Member 14743579 15-Apr-21 6:44am    
I know but every time socket is empty when my server trying to read the messages comes form client.
Greg Utas 15-Apr-21 7:55am    
Maybe the clients aren't sending properly. Or maybe you're not reading the socket that the server allocated when it accepted the connection.
Richard MacCutchan 15-Apr-21 8:50am    
Then you need to use the debugger to find out why.

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