How can I use Java.net.* to connect two computers on a network?

Question

Java

Good afternoon, ladies and gentlemen. I have two computers with Internet access. On the first, following the manuals, I write the following code:

import java.net.*;
import java.io.*;
 
public class Lied {
       
        public static void main (String args[]) throws IOException{
                try(ServerSocket serverSocket = new ServerSocket(11111)){
                        while(true){
                                try (Socket socket = serverSocket.accept()){
                                        serveClient(socket);
                                }
        }
}
}
 
private static void serveClient(Socket socket) throws IOException {
        InputStream inputStream = socket.getInputStream();
        OutputStream outputStream = socket.getOutputStream();
       
        while(true){
                int request = inputStream.read();
                if (request == -1) {
                        break;
                }
                outputStream.write(request*request);
                System.out.println("Получили число: " + request);
                outputStream.flush();
        }
}
}

The program receives a number through port 11111 and, squaring it, sends it back. Using an online service, I found out the name of the computer on which the program above is written. On the second computer I run:

import java.net.*;
import java.io.*;
public class inet{
        public static void main(String args[]) throws Exception{
                try(Socket socket = new Socket("93-81-119-229.broadband.corbina.ru",11111)){
                        OutputStream outputStream = socket.getOutputStream();
                        outputStream.write(5);
                        outputStream.flush();
                       
                        InputStream inputStream = socket.getInputStream();
                        int response = inputStream.read();
                       
                        System.out.println(response);
                }
        }
}

Here "93-81-119-229.broadband.corbina.ru" is the hostname of the first computer. For some reason that I don't understand, the second program tries to connect for a while and throws a "Connection time out" exception. What am I doing wrong? I also ask you to indicate the necessary literature that can help with the development of the topic of networks. Thank you.

Answer 1

This host / ip is pinged, but it is not possible to connect to it on port 80/11111.
Perhaps the matter is in firewalls, routers, forwarded ports, etc.