Stun server doesnt work / ipv6 ? about p2p HOT 5 OPEN

using System;
using System.Net;
using NATUPNPLib;

namespace UPnPExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // Open a port
            OpenPort(8080, "TCP", "Test Port");

            // Wait for user input
            Console.WriteLine("Press any key to close the port...");
            Console.ReadKey();

            // Close the port
            ClosePort(8080, "TCP");

            Console.WriteLine("Port closed. Press any key to exit...");
            Console.ReadKey();
        }

        static void OpenPort(int port, string protocol, string description)
        {
            try
            {
                UPnPNAT upnpnat = new UPnPNAT();
                IStaticPortMappingCollection mappings = upnpnat.StaticPortMappingCollection;

                if (mappings != null)
                {
                    string localIp = GetLocalIPAddress();
                    mappings.Add(port, protocol, port, localIp, true, description);
                    Console.WriteLine($"Port {port}/{protocol} opened successfully for IP {localIp}.");
                }
                else
                {
                    Console.WriteLine("Unable to retrieve port mappings.");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Failed to open port {port}/{protocol}: {ex.Message}");
            }
        }

        static void ClosePort(int port, string protocol)
        {
            try
            {
                UPnPNAT upnpnat = new UPnPNAT();
                IStaticPortMappingCollection mappings = upnpnat.StaticPortMappingCollection;

                if (mappings != null)
                {
                    mappings.Remove(port, protocol);
                    Console.WriteLine($"Port {port}/{protocol} closed successfully.");
                }
                else
                {
                    Console.WriteLine("Unable to retrieve port mappings.");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Failed to close port {port}/{protocol}: {ex.Message}");
            }
        }

        static string GetLocalIPAddress()
        {
            var host = Dns.GetHostEntry(Dns.GetHostName());
            foreach (var ip in host.AddressList)
            {
                if (ip.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork || 
                    ip.AddressFamily == System.Net.Sockets.AddressFamily.InterNetworkV6)
                {
                    return ip.ToString();
                }
            }
            throw new Exception("No network adapters with an IPv4 or IPv6 address in the system!");
        }
    }
}