I do not understand where is problem?

Question

The basic idea is the following, we have a client and server when the client connects to a server it sends the basic information (IP address and port) and on the basis of this information the server connects to the client, this is just a test program that should serve as part of the solution. The task to be solved by the following, I have three entities client, server and workstation. The client sends a job to the server, the server forward the work to a free station and awaits the results of processing, the workstation may employ other workstations and communicate directly with them (not through the server), that is why it is necessary to make this type of communication. This code working on local computer but when I try it on network it does not work.
import java.io.Serializable;
import java.net.InetAddress;
import java.net.UnknownHostException;
public class ClientInfo implements Serializable {
    private String name;
    private String ip;
    private int serverPort;
    public ClientInfo() {
        name = "Unknown Client";
        try {
            ip = InetAddress.getLocalHost().getHostAddress();
        } catch (UnknownHostException e) {
            ip = "Unknown Host";
    public String getIp() {
        return ip;
import java.io.Serializable;
import java.net.InetAddress;
import java.net.UnknownHostException;
public class ServerInfo implements Serializable {
    private String name;
    private String ip;
    private int serverPort;
    public ServerInfo() {
        name = "Unknown Client";
        try {
            ip = InetAddress.getLocalHost().getHostAddress();
        } catch (UnknownHostException e) {
            ip = "Unknown Host";
    public String getIp() {
        return ip;
import java.io.IOException;
import java.net.ServerSocket;
public class MultiClient implements Runnable {
        private ServerSocket serverSocket = null;
        private boolean listening = true;
        private Thread t;
        MultiClient () {
            t = new Thread(this);
            t.start();
        public void run() {
            try {
                serverSocket = new ServerSocket(4003);
                while (listening)
                    new MultiClientThread(serverSocket.accept()).start();
                serverSocket.close();
            } catch (IOException e) {
                System.err.println("Could not listen on port: 4003.");
                System.exit(-1);
import java.io.IOException;
import java.net.ServerSocket;
public class MultiServer {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = null;
        boolean listening = true;
        try {
            serverSocket = new ServerSocket(4004);
        } catch (IOException e) {
            System.err.println("Could not listen on port: 4004.");
            System.exit(-1);
        while (listening)
         new MultiServerThread(serverSocket.accept()).start();
        serverSocket.close();
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
public class MultiClientThread extends Thread {
        private Socket socket = null;
    public MultiClientThread(Socket socket) {
     super("MultiClientThread");
     this.socket = socket;
    public void run() {
        try {
            ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream()); out.flush();
            ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
            Object object = in.readObject();
            if (object instanceof ServerInfo) {
                ServerInfo info = (ServerInfo)object;
                System.out.println(info.getIp());
            out.writeObject(new Integer(100));
     } catch (IOException e) {
         e.printStackTrace();
        catch (ClassNotFoundException e) {}
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
public class MultiServerThread extends Thread {
        private Socket socket = null, cSocket = null;
        ObjectOutputStream out = null; ObjectInputStream in = null;
        ObjectOutputStream cOut = null; ObjectInputStream cIn = null;
    public MultiServerThread(Socket socket) {
     super("MultiServerThread");
     this.socket = socket;
    public void run() {
        try {
            out = new ObjectOutputStream(socket.getOutputStream()); out.flush();
            in = new ObjectInputStream(socket.getInputStream());
            try {
                Object object = in.readObject();
                if (object instanceof ClientInfo) {
                    ClientInfo info = (ClientInfo)object;
                    System.out.println(info.getIp());
                    // Connect on client
                    cSocket = new Socket(info.getIp(), 4003);
                    cOut = new ObjectOutputStream(cSocket.getOutputStream()); cOut.flush();
                    cIn = new ObjectInputStream(cSocket.getInputStream());
                    ServerInfo sInfo = new ServerInfo();
                    cOut.writeObject(sInfo);
                    Object object2 = cIn.readObject();
                    if (object2 instanceof Integer) {
                        Integer broj = (Integer)object2;
                        System.out.println(broj);
            catch (ClassNotFoundException e) {}
     } catch (IOException e) {
         e.printStackTrace();
        try {
            out.close();
            in.close();
            socket.close();
            cOut.close();
            cIn.close();
            cSocket.close();
        } catch (IOException e) {}
import java.io.*;
import java.net.*;
public class Client {
    public static void main(String[] args) throws IOException {
        Socket socket = null;
        ObjectOutputStream out = null; ObjectInputStream in = null;
        try {
            MultiClient multiclient = new MultiClient();
            // Here goes server IP at the moment there is local IP
            socket = new Socket("192.168.1.3", 4004);
            out = new ObjectOutputStream(socket.getOutputStream()); out.flush();
            in = new ObjectInputStream(socket.getInputStream());
            ClientInfo info = new ClientInfo();
            out.writeObject(info);
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host.");
            System.exit(1);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection.");
            System.exit(1);
        out.close();
        in.close();
        socket.close();
}

Answer 1

when I try it on network it does not work. The information content of that statement is approximately one bit.
Doesn't work how? What happens instead? What exception? What message? What stack trace? What unexpected behaviour?