Gameobject not being set active in 'catch'. I've checked everything

Here is what I'm trying to do:

Trying to check if there's internet connection or no. If there is no internet connection, I want to set active a panel showing 'no internet connection'.

I dragged the panel to the inspector. The script which sets this panel active is on a gameobject which is active in hierarchy.

Here is the code:

public GameObject NoInternetConnectionPanel;

private void Start()
{
    //Check Internet Connection
    InvokeRepeating("CheckInternetConnection", 0f, 1f);
}

private void CheckInternetConnection()
{
    var request = WebRequest.Create("http://google.com");
    request.Method = "HEAD";

    request.BeginGetResponse(result =>
    {
        try
       {
            using (var response = request.EndGetResponse(result) as HttpWebResponse)
            {
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    Debug.Log("Internet connection available");
                }
                /*else
                {
                    Debug.Log("No internet connection");
                }*/
            }
        }
        catch (WebException ex)
        {
            Debug.Log("No internet connection");
            NoInternetConnectionPanel.SetActive(true);
        }
    }, null);
    
    StartCoroutine(WaitAndCheck());
}
private IEnumerator WaitAndCheck()
{
    yield return new WaitForSeconds(1f);  
}

The debug log message "no internet connection" is being shown in console. But the 'NoInternetConnectionPanel.SetActive(true)' is not working.

What could be the issue?

That's most probably because it is being executed on another any thread which is not supported by most of the Unity API. In general you shouldn't be using WebRequest at all but rather use UnityWebRequest in a Coroutine.

Also not btw that your WaitAndCheck routine doesn't do anything at all.

I would rather use something like e.g.

public GameObject NoInternetConnectionPanel;

private IEnumerator Start()
{
    while(true)
    {
        yield return CheckInternetConnection();
        yield return new WaitForSeconds(1f);
    }
}

private IEnumerator CheckInternetConnection()
{
    using(var request = UnityWebRequest.Head("http://google.com"))
    {
        yield return request.SendWebRequest();

        var connection = request.result == UnityWebRequest.Result.Success;

        NoInternetConnectionPanel.SetActive(! connection);

        if(connection)
        {
            Debug.Log("Internet connection available");      
        }
        else
        {
            Debug.LogWarning("No internet connection");
        }
    }
}

Instead of using a we request at all you can also use a simple Ping which is often used with e.g. 8.8.8.8, Google's global DNS server.

private IEnumerator CheckInternetConnection()
{
    var ping = new Ping("8.8.8.8");
    var maxPingTime = 1f; // maximum time to wait before declaring the ping as failed
    var connection = false;
    for(var timePassed = 0f; timePassed <= maxPingTime; timePassed += Time.deltaTime)
    {
        if(ping.isDone)
        {
            connection = true;
            break;
        }
    }

    NoInternetConnectionPanel.SetActive(! connection);

    if(connection)
    {
        Debug.Log("Internet connection available");      
    }
    else
    {
        Debug.LogWarning("No internet connection");
    }
}