What is the problem with TCP connection?

Question

Windows

Hello! Faced such a problem. There are two apps, one is the server and the other is the client.
When exchanging locally, everything worked, as soon as I put the server on the server with Windows, an error occurs, although the IP and PORT specified are correct ..
Error: System.Net.Sockets.SocketException: "The attempt to establish a connection was unsuccessful, Another computer did not receive the required response in the required time, or an already established connection was terminated due to an incorrect response from an already connected computer 18.220.144.236:8888 "
I tried to disable the firewalls on both computers, it did not help.
Here is the client code:

spoiler

using System;
using System.Net.Sockets;
using System.Text;
 
namespace ConsoleClient
{
    class Program
    {
        const int port = 8888;
        const string address = "18.220.144.236";
        static void Main(string[] args)
        {
            Console.Write("Введите свое имя:");
            string userName = Console.ReadLine();
            TcpClient client = null;
            
                client = new TcpClient(address, port);
                NetworkStream stream = client.GetStream();
 
                while (true)
                {
                    Console.Write(userName + ": ");
                    // ввод сообщения
                    string message = Console.ReadLine();
                    message = String.Format("{0}: {1}", userName, message);
                    // преобразуем сообщение в массив байтов
                    byte[] data = Encoding.Unicode.GetBytes(message);
                    // отправка сообщения
                    stream.Write(data, 0, data.Length);
 
                    // получаем ответ
                    data = new byte[64]; // буфер для получаемых данных
                    StringBuilder builder = new StringBuilder();
                    int bytes = 0;
                    do
                    {
                        bytes = stream.Read(data, 0, data.Length);
                        builder.Append(Encoding.Unicode.GetString(data, 0, bytes));
                    }
                    while (stream.DataAvailable);
 
                    message = builder.ToString();
                    Console.WriteLine("Сервер: {0}", message);
                }
            
        }
    }
}

And here is the server code: the ClientObjects class

spoiler

using System;
using System.Net.Sockets;
using System.Text;
 
namespace ConsoleServer
{
    public class ClientObject
    {
        public TcpClient client;
        public ClientObject(TcpClient tcpClient)
        {
            client = tcpClient;
        }
 
        public void Process()
        {
            NetworkStream stream = null;
            try
            {
                stream = client.GetStream();
                byte[] data = new byte[64]; // буфер для получаемых данных
                while (true)
                {
                    // получаем сообщение
                    StringBuilder builder = new StringBuilder();
                    int bytes = 0;
                    do
                    {
                        bytes = stream.Read(data, 0, data.Length);
                        builder.Append(Encoding.Unicode.GetString(data, 0, bytes));
                    }
                    while (stream.DataAvailable);
 
                    string message = builder.ToString();
 
                    Console.WriteLine(message);
                    // отправляем обратно сообщение в верхнем регистре
                    message = message.Substring(message.IndexOf(':') + 1).Trim().ToUpper();
                    data = Encoding.Unicode.GetBytes(message);
                    stream.Write(data, 0, data.Length);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                if (stream != null)
                    stream.Close();
                if (client != null)
                    client.Close();
            }
        }
    }
}

And the Program class:

spoiler

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
 
namespace ConsoleServer
{
    class Program
    {
        const int port = 8888;
        static TcpListener listener;
        static void Main(string[] args)
        {
            try
            {
                listener = new TcpListener(port);
                listener.Start();
                Console.WriteLine("Ожидание подключений...");
 
                while (true)
                {
                    TcpClient client = listener.AcceptTcpClient();
                    ClientObject clientObject = new ClientObject(client);
 
                    // создаем новый поток для обслуживания нового клиента
                    Thread clientThread = new Thread(new ThreadStart(clientObject.Process));
                    clientThread.Start();
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                if (listener != null)
                    listener.Stop();
            }
        }
    }
}

Client OS Windows 7
Server OS Windows 10
.NET Framework Version - 4.5.2

Answer 1

What specific device has the address 18.220.144.236?
Most likely this is the address of the router on which NAT works, and it prevents you from gaining access. You need to forward the port in the NAT settings on the router.