object reference not set to an instance of an object แก้ยังไง

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

namespace Wifi_Control
{
    public partial class Form1 : Form
    {
        private Socket client;
        private Thread receiver;
        private byte[] data = new byte[1024];
        private byte[] data1 = new byte[1024];
        public Form1()
        {
            InitializeComponent();
        }
        private void connected(IAsyncResult iar)
        {
            try
            {
                client.EndConnect(iar);

                lblsta.Text = "Connected";
                receiver = new Thread(new ThreadStart(ReceiveData));
                receiver.Start();
                
            }

            catch
            {
                MessageBox.Show("ไม่สามารถเชื่อต่อได้ โปรดตรวจสอบข้อมูล");

            }

        }

        private void ReceiveData()  //รับ packet จาก Client/Server
        {
            int recv;
            string strData ;
            

            while (client.Connected) //เช็คสถานะการเชื่อมต่อ
            {
                    
                try
                {
                    recv = client.Receive(data); // คืนค่าเป็นความยาวของ Data 
                    strData = Encoding.Default.GetString(data, 0, recv);
                    string[] getdata = strData.Split(',');
                    textBox1.Text = getdata[0];
                    textBox2.Text = getdata[1];
                    
                    richTextBox2.AppendText("รับ: " + strData + "\n");

                    
                    
                    
                }
                catch (SocketException ex)
                {
                    MessageBox.Show(ex.Message, "Client");
                }
            }
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void BtnCon_Click(object sender, EventArgs e)
        {
            try
            {
                client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                IPEndPoint iep = new IPEndPoint(IPAddress.Parse(TxtIP.Text), int.Parse(TxtPort.Text));
                client.BeginConnect(iep, new AsyncCallback(connected), client);

            }
            catch
            {
                MessageBox.Show("เชื่อมต่อเซิฟเวอร์ไม่สำเร็จ โปรดตรวจความถูกต้อง");
            }
        }

        private void label2_Click(object sender, EventArgs e)
        {

        }
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            reg["port"] = TxtPort.Text;
            reg["url"] = TxtIP.Text;
            try
            {
                BtnCon_Click(sender, e);
            }
            catch
            {
            }
        }
        string port = "";
        string url = "";
        MyReg reg = new MyReg("ArduinoAll");
        private void Form1_Load(object sender, EventArgs e)
        {

            timer1.Interval = 1000;
            timer1.Enabled = true;
           
           

            try
            {
                port = reg["port"].ToString();
                url = reg["url"].ToString();

                TxtIP.Text = url;
                TxtPort.Text = port;
            }
            catch
            {
                reg["port"] = "";
                reg["url"] = "";
            }

        
        }

        private void BtnDis_Click(object sender, EventArgs e)
        {
            if (client.Connected)
            {  // receiver.Abort();
                receiver.Abort(client);
                lblsta.Text = "Disconnected";
                client.Close(5);
            }
            else
            {
                MessageBox.Show("ไม่มีการเชื่อมต่อ");
            }
        }
        private void SendData(IAsyncResult iar)
        {
            try
            {
                Socket remote = (Socket)iar.AsyncState;
                int sent = remote.EndSend(iar);
            }
            catch (SocketException ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        private void button1_Click(object sender, EventArgs e)
        {
            InputTxt.Text = "ON";
            BtnSend_Click(sender, e);
        }

       private void timer1_Tick(object sender, EventArgs e)
        {
            
            
           ReceiveData();

        }

        
    }
}