Your code doing not right thing. When you run “TCPPacketServer” it have to write “Opening port…” and after  when you run"TCPPacketClient" it have to write “Enter the data packet:” after you write anything like "Client1" it will return this info to “TCPPacketServer” and "TCPPacketServer" will write "Recieving From Clients Packet’s serialNo#1
and packet’s Data is CLIENT1"
it have to look like this-->

running of TCPPacketServer:
Opening port…

Recieving From Clients Packet’s serialNo#1
and packet’s Data is THIS IS CLIENT1
Recieving From Clients Packet’s serialNo#1
and packet’s Data is THIS IS CLIENT2

running of TCPPacketClient:
Enter the data packet: this is Client1
FROM SERVER:Packet SerialNo#1 is recieved
Enter the data packet: this is Client2
FROM SERVER:Packet SerialNo#2 is recieved

NOTE: that "THIS IS CLIENT1" and "THIS IS CLIENT2" is info from "Clients" class and anything could be written on their places
Here is the code of program that you have to fix-->import java.io.*;
import java.net.*;
import java.util.concurrent.*;

public class TCPPacketServer {
    private static int port = 1024;
    private static ExecutorService pool = Executors.newFixedThreadPool(10);

    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(port);

            while (true) {
                Socket clientSocket = serverSocket.accept();
                pool.execute(new ClientHandler(clientSocket));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static class ClientHandler implements Runnable {
        private Socket clientSocket;

        public ClientHandler(Socket socket) {
            this.clientSocket = socket;
        }

        public void run() {
            try {
                PrintStream ps = new PrintStream(clientSocket.getOutputStream());

                while (true) {
                    InputStream is = clientSocket.getInputStream();
                    byte[] buffer = new byte[1024];
                    int bytesRead = is.read(buffer);

                    if (bytesRead > 0) {
                        ByteArrayInputStream bais = new ByteArrayInputStream(buffer, 0, bytesRead);
                        ObjectInputStream ois = new ObjectInputStream(bais);
                        Packet packet = (Packet) ois.readObject();
                        System.out.println("FROM CLIENT " + clientSocket.getRemoteSocketAddress() + ": Packet SerialNo#" + packet.getSerialNo() + " is received");

                        if (packet.getData().equals("CLOSE")) {
                            break;
                        }

                        Packet responsePacket = new Packet(packet.getSerialNo(), packet.getData().toUpperCase());
                        ByteArrayOutputStream baos = new ByteArrayOutputStream();
                        ObjectOutputStream oos = new ObjectOutputStream(baos);
                        oos.writeObject(responsePacket);

                        byte[] responseBuffer = baos.toByteArray();
                        ps.write(responseBuffer);
                    }
                }

                ps.close();
                clientSocket.close();
            } catch (IOException | ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    }
}
import java.io.*;
import java.net.*;

public class TCPPacketClient {
    private static String[] output = {"–Enter the data packet: "};

    public static void main(String[] args) {
        try {
            Socket socket = new Socket("localhost", 1024);

            PrintStream ps = new PrintStream(socket.getOutputStream());

            BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
            String line = "";
            int serialNo = 1;
            while (!line.equals("CLOSE")) {
                System.out.print(output[0]);
                line = input.readLine();

                Packet packet = new Packet(serialNo++, line);
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                ObjectOutputStream oos = new ObjectOutputStream(baos);
                oos.writeObject(packet);

                byte[] buffer = baos.toByteArray();
                ps.write(buffer);

                InputStream is = socket.getInputStream();
                byte[] responseBuffer = new byte[1024];
                int bytesRead = is.read(responseBuffer);

                if (bytesRead > 0) {
                    ByteArrayInputStream bais = new ByteArrayInputStream(responseBuffer, 0, bytesRead);
                    ObjectInputStream ois = new ObjectInputStream(bais);
                    Packet responsePacket = (Packet) ois.readObject();
                    System.out.println("FROM SERVER: Packet SerialNo#" + responsePacket.getSerialNo() + ", Data: " + responsePacket.getData());
                }
            }

            ps.close();
            socket.close();
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
}
import java.io.Serializable;

public class Packet implements Serializable {
    private int serialNo;
    private String data;

    public Packet(int serialNo, String data) {
        this.serialNo = serialNo;
        this.data = data;
    }

    public String getData() {
        return data;
    }

    public int getSerialNo() {
        return serialNo;
    }
}import java.io.*;
import java.net.*;

public class MTServer {
    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(8080);
            System.out.println("Waiting for client request…");
            Socket socket = serverSocket.accept();
            System.out.println("New client is pop up!");

            BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            PrintStream ps = new PrintStream(socket.getOutputStream());

            String response;
            while (true) {
                System.out.print("Server: ");
                String line = new BufferedReader(new InputStreamReader(System.in)).readLine();
                ps.println(line);

                response = br.readLine();
                if (response.equals("CLOSE")) {
                    break;
                }
                System.out.println("Clients: " + response);
            }

            ps.close();
            br.close();
            socket.close();
            System.out.println("End of conversation");
        } catch (IOException e) {
            System.err.println(e);
        }
    }
}import java.io.*;
import java.net.*;

public class Clients {
    public static void main(String[] args) {
        try {
            Socket socket = new Socket("localhost", 8080);
            System.out.println("Request sent successfully");

            BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            PrintStream ps = new PrintStream(socket.getOutputStream());
            String response;

            while (true) {
                response = br.readLine();
                System.out.println("Server: " + response);

                System.out.print("Clients: ");
                String line = new BufferedReader(new InputStreamReader(System.in)).readLine();
                ps.println(line);

                if (line.equals("CLOSE")) {
                    break;
                }
            }

            ps.close();
            br.close();
            socket.close();
            System.out.println("End of conversation");
        } catch (IOException e) {
            System.err.println(e);
        }
    }
}