A connection attempt between clint and the server failed in the chat application

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C#6.0

My problem is that I have a code for the server and a code for the Clint and when I do not connect,
What is the solution?
This is the server code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;


namespace Server_TCP_WINFORMS
{
    public partial class Form1 : Form
    {
        int i;
        TcpListener server = new TcpListener(IPAddress.Any,1980); // Creates a TCP Listener To Listen to Any IPAddress trying to connect to the program with port 1980
       

        NetworkStream stream; //Creats a NetworkStream (used for sending and receiving data)
        TcpClient client; // Creates a TCP Client
        byte[] datalength = new byte[4]; // creates a new byte with length 4 ( used for receivng data's lenght)


        public Form1()
        {
            InitializeComponent();

        }

        public void ServerReceive()
        {
            stream = client.GetStream(); //Gets The Stream of The Connection
            new Thread(() => // Thread (like Timer)
            {
                while ((i = stream.Read(datalength, 0, 4)) != 0)//Keeps Trying to Receive the Size of the Message or Data
                {
                    // how to make a byte E.X byte[] examlpe = new byte[the size of the byte here] , i used BitConverter.ToInt32(datalength,0) cuz i received the length of the data in byte called datalength :D
                    byte[] data = new byte[BitConverter.ToInt32(datalength, 0)]; // Creates a Byte for the data to be Received On
                    stream.Read(data, 0, data.Length); //Receives The Real Data not the Size
                    this.Invoke((MethodInvoker)delegate // To Write the Received data
                    {
                        txtLog.Text += System.Environment.NewLine + "Client : " + Encoding.Default.GetString(data); // Encoding.Default.GetString(data); Converts Bytes Received to String
                    });
                }
            }).Start(); // Start the Thread
            MessageBox.Show("start thread 1");
        }

        private void btnlisten_Click(object sender, EventArgs e)
        {
            server.Start(); // Starts Listening to Any IPAddress trying to connect to the program with port 1980
            MessageBox.Show("Waiting For Connection");
            new Thread(() => // Creates a New Thread (like a timer)
            {
                if(
                client == server.AcceptTcpClient()) //Waits for the Client To Connect
                if (client.Connected) // If you are connected
                {
                    
                    ServerReceive(); //Start Receiving
                }
            }).Start();
            
        }

        public void serversend(string msg)
        {

            stream = client.GetStream(); //Gets The Stream of The Connection
            byte[] data; // creates a new byte without mentioning the size of it cuz its a byte used for sending
            data = Encoding.Default.GetBytes(msg); // put the msg in the byte ( it automaticly uses the size of the msg )
            int length = data.Length; // Gets the length of the byte data
            byte[] datalength = new byte[4]; // Creates a new byte with length of 4
            datalength = BitConverter.GetBytes(length); //put the length in a byte to send it
            stream.Write(datalength, 0, 4); // sends the data's length
            stream.Write(data, 0, data.Length); //Sends the real data
        }

        private void button1_Click(object sender, EventArgs e)
        {

            if (client.Connected) // if the client is connected
            {
                serversend(txtsend.Text); // uses the Function ClientSend and the msg as txtSend.Text
                label3.Text = "send is ok";
            }

        }



        }

        }

This is the Clint Code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace Client1
{
    public partial class Form1 : Form
    {


        int i;
        TcpClient client; // Creates a TCP Client
        NetworkStream stream; //Creats a NetworkStream (used for sending and receiving data)
        byte[] datalength = new byte[4]; // creates a new byte with length 4 ( used for receivng data's lenght)



        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void btnConnect_Click(object sender, EventArgs e)
        {



            try
            {
                client = new TcpClient("127.0.0.1", 1980); //Trys to Connect
                ClientReceive(); //Starts Receiving When Connected
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message); // Error handler :D
            }



        }



        public void ClientReceive()
        {

            stream = client.GetStream(); //Gets The Stream of The Connection
            new Thread(() => // Thread (like Timer)
            {
                while ((i = stream.Read(datalength, 0, 4)) != 0)//Keeps Trying to Receive the Size of the Message or Data
                {
                    // how to make a byte E.X byte[] examlpe = new byte[the size of the byte here] , i used BitConverter.ToInt32(datalength,0) cuz i received the length of the data in byte called datalength :D
                    byte[] data = new byte[BitConverter.ToInt32(datalength, 0)]; // Creates a Byte for the data to be Received On
                    stream.Read(data, 0, data.Length); //Receives The Real Data not the Size
                    this.Invoke((MethodInvoker)delegate // To Write the Received data
                    {
                        txtLog.Text += System.Environment.NewLine + "Server : " + Encoding.Default.GetString(data); // Encoding.Default.GetString(data); Converts Bytes Received to String
                    });
                }
            }).Start(); // Start the Thread
        }


        public void ClientSend(string msg)
        {
            stream = client.GetStream(); //Gets The Stream of The Connection
            byte[] data; // creates a new byte without mentioning the size of it cuz its a byte used for sending
            data = Encoding.Default.GetBytes(msg); // put the msg in the byte ( it automaticly uses the size of the msg )
            int length = data.Length; // Gets the length of the byte data
            byte[] datalength = new byte[4]; // Creates a new byte with length of 4
            datalength = BitConverter.GetBytes(length); //put the length in a byte to send it
            stream.Write(datalength, 0, 4); // sends the data's length
            stream.Write(data, 0, data.Length); //Sends the real data
        }


        private void btnSend_Click(object sender, EventArgs e)
        {

            TcpClient client = new TcpClient();

            if (client.Connected) // if the client is connected
            {
               
                ClientSend(txtSend.Text); // uses the Function ClientSend and the msg as txtSend.Text
                MessageBox.Show("the client is connected");
               
            }

        }
    }
}

What I have tried:

I tried to fetch several code from the Microsoft site without a result