How to make TCP client server connection

InvalidOperationException was unhandled.
An unhandled exception of type 'System.InvalidOperationException' occurred in System.dll

static void Main(string[] args)
        {
            TcpListener serverSocket = new TcpListener(8281);
            int requestCount = 0;
            TcpClient clientSocket = default(TcpClient);
            serverSocket.Start();
            Console.WriteLine(" >> Server Started");
            clientSocket = serverSocket.AcceptTcpClient();
            Console.WriteLine(" >> Accept connection from client");
            requestCount = 0;
            while ((true))
            {
                try
                {
                    requestCount = requestCount + 1;
                    NetworkStream networkStream = clientSocket.GetStream();
                    byte[] bytesFrom = new byte[10025];
                    networkStream.Read(bytesFrom, 0, (int)clientSocket.ReceiveBufferSize);
                    string dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom);
                    dataFromClient = dataFromClient.Substring(0, dataFromClient.IndexOf("$"));
                    Console.WriteLine(" >> Data from client - " + dataFromClient);
                    string serverResponse = "Last Message from client" + dataFromClient;
                    Byte[] sendBytes = Encoding.ASCII.GetBytes(serverResponse);
                    networkStream.Write(sendBytes, 0, sendBytes.Length);
                    networkStream.Flush();
                    Console.WriteLine(" >> " + serverResponse);
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
            }

            clientSocket.Close();
            serverSocket.Stop();
            Console.WriteLine(" >> exit");
            Console.ReadLine();

        }

    public partial class Form1 : Form
    {
        System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            msg("Client Started");
            clientSocket.Connect("127.0.0.1", 8281);
            label1.Text = "Client Socket Program - Server Connected ...";
        }


        public void msg(string mesg)
        {
            textBox1.Text = textBox1.Text + Environment.NewLine + " >> " + mesg;
        }

        private void button1_Click_1(object sender, EventArgs e)
        {
            NetworkStream serverStream = clientSocket.GetStream();
            byte[] outStream = System.Text.Encoding.ASCII.GetBytes(textBox2.Text + "$");
            serverStream.Write(outStream, 0, outStream.Length);
            serverStream.Flush();

            byte[] inStream = new byte[10025];
            serverStream.Read(inStream, 0, (int)clientSocket.ReceiveBufferSize);
            string returndata = System.Text.Encoding.ASCII.GetString(inStream);
            msg(returndata);
            textBox2.Text = "";
            textBox2.Focus();
        }
}