Server.cs

    public class Server : IDisposable {

        private static JavaScriptSerializer JSON = new JavaScriptSerializer();
        
        class Message {
            public string Content;
        }

        class Client : IDisposable {
            Socket socket;
            StringBuilder sb = new StringBuilder();
            Server server;
            const int BufferSize = 1024;
            byte[] Buffer = new byte[BufferSize];

            private void Recive() {
                socket.BeginReceive(Buffer, 0, BufferSize, SocketFlags.None, result => {
                    try {
                        int bytesRead = socket.EndReceive(result);
                        if (bytesRead > 0) {
                            sb.Append(UTF8.GetString(Buffer, 0, bytesRead));

                            var content = sb.ToString();
                            if (content.IndexOf("\r\n\r\n") != -1) {
                                sb.Length -= 2;
                                MessageHandeler(sb.ToString());
                                Buffer = new byte[BufferSize];
                                sb.Clear();
                            }
                        }
                        Recive();
                    } catch (Exception) {
                        Console.WriteLine("wow coś sie popsuło");
                    }
                }, null);
            }

            private void MessageHandeler(string _message) {
                var message = JSON.Deserialize<Message>(_message);
                onMessage?.Invoke(this, message);
                Console.WriteLine(message.Content);
            }

            public Client(Socket socket, Server s) {
                this.socket = socket;
                server = s;
                Recive();
            }

            public void Send(string message) {
                var bytes = UTF8.GetBytes(message);

                socket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, result => {
                    int bytesSend = socket.EndSend(result);
                    Console.WriteLine($"send {}");
                }, null);
            }

            public event EventHandler<Message> onMessage;

            public void Dispose() {
                socket.Shutdown(SocketShutdown.Both);
                socket.Close();
                server.Clients.Remove(this);
            }
        }

        Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

        LinkedList<Client> Clients = new LinkedList<Client>();

        public void Listen(int port) {
            IPEndPoint endPoint = new IPEndPoint(IPAddress.Any, port);

            socket.Bind(endPoint);
            socket.Listen(100);

            AcceptConnections();
            Console.WriteLine($"Server listening at port: {port}");
        }

        private void AcceptConnections() {
            socket.BeginAccept(result => {
                AcceptConnections();

                Socket handler = socket.EndAccept(result);
                Clients.AddFirst(new Client(handler, this));
            }, null);
        }

        public void Dispose() {
            throw new NotImplementedException();
        }
    }