InternetConnectionChecker.cs

using System.Net;
using UnityEngine;
 
namespace SCG.SpaceAdMobile
{
    public enum CheckInternetConnectionType : byte
    {
        [Tooltip("Uses Unity's Application.internetReachability signal.")]
        Simple = 0,
        [Tooltip("Performs an actual network call (HTTP HEAD) to a known endpoint.")]
        Request = 1
    }

    public interface IInternetConnectionChecker
    {
        bool CheckInternetConnection();
    }

    public class SimpleInternetConnectionChecker : IInternetConnectionChecker
    {
        public bool CheckInternetConnection() => Application.internetReachability != NetworkReachability.NotReachable;
    }

    public class RequestInternetConnectionChecker : IInternetConnectionChecker
    {
        public string RequestUrl { get; set; } = "http://unity.com";

        public bool CheckInternetConnection()
        {
            const string requestMethod = "HEAD";
            try
            {
                var request = (HttpWebRequest)WebRequest.Create(RequestUrl);
                request.Method = requestMethod;
                using var response = (HttpWebResponse)request.GetResponse();
                return response.StatusCode == HttpStatusCode.OK;
            }
            catch
            {
                return false;
            }
        }
    }
}