Problem with thread exception

using UnityEngine;
using UnityEngine.UI;
using System;
using System.Text;
using System.Collections;
using System.Net;
using System.Net.Sockets;
using System.Threading;

public class ConnectionsHandler : MonoBehaviour
{
    private static Socket ServerSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
    public GameObject ConnectButton;
    public GameObject SendButton;
    public Text ipAdress;
    public Text port;
    public Text serverResponse;
    public Text textToBeSent;
    private bool Connected;

    void Start()
    {
        Connected = false;
    }

    public void ConnectToServer()
    {
        int attempts = 0;
        while (!ServerSocket.Connected)
        {
            try
            {
                attempts++;
                ServerSocket.Connect(IPAddress.Parse(ipAdress.text), int.Parse(port.text));
            }
            catch (SocketException)
            {
                Debug.Log("Connection attempts: " + attempts.ToString());
            }
            if (attempts >= 4)
            {
                return;
            }
        }
        Debug.Log("Connected");
        serverResponse.text = "Connected with Server";
        Connected = true;
    }

    public void SendTextStream()
    {
        if (Connected == true)
        {
            if (textToBeSent.text != string.Empty)
            {
                string text = textToBeSent.text;
                byte[] buffer = Encoding.ASCII.GetBytes(text);
                ServerSocket.Send(buffer);
                textToBeSent.text = string.Empty;
                StartCoroutine_Auto(CatchFilesLoop());
            }
        }
    }

    IEnumerator CatchFilesLoop()
    {
        yield return new WaitForSeconds(1f);
        byte[] receivedBuf = new byte[1024];
        int rec = ServerSocket.Receive(receivedBuf);
        byte[] data = new byte[rec];
        Array.Copy(receivedBuf, data, rec);
        serverResponse.text = Encoding.ASCII.GetString(data);
    }
}