Not able to establish tls connection with azure event grid mqtt server about mqttnet HOT 2 CLOSED

using MQTTnet.Client;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography.X509Certificates;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace MQTTnet.Samples.Client;

public static class Client_Connection_pub
{
    public static async Task connect_with_pub()
    {
        string hostname = "publishjsonmqtteventgridns.westeurope-1.ts.eventgrid.azure.net";
        string clientId = "client1-session1";  //client ID can be the session identifier.  A client can have multiple sessions using username and clientId. 
        string x509_pem = @"C:\Users\INNEBIS1/certificate/client1-authn-ID.pem";  //Provide your client certificate .cer.pem file path
        string x509_key = @"C:\Users\INNEBIS1/certificate/client1-authn-ID.key";  //Provide your client certificate .key.pem file path

        // Load certificate and private key from PEM files
        var certificate = new X509Certificate2(X509Certificate2.CreateFromPemFile(x509_pem, x509_key).Export(X509ContentType.Pkcs12));

        // Add the loaded certificate to a certificate collection
        X509Certificate2Collection certificates = new X509Certificate2Collection
        {
            certificate
        };

        var mqttClient = new MqttFactory().CreateMqttClient();
        var connAck = await mqttClient!.ConnectAsync(new MqttClientOptionsBuilder()
            .WithTcpServer(hostname, 8883)
            .WithClientId(clientId)
            .WithCredentials("client1-authn-ID", "")  //use client authentication name in the username
            .WithTlsOptions(new MqttClientTlsOptionsBuilder()
                .WithSslProtocols(System.Security.Authentication.SslProtocols.Tls12 | System.Security.Authentication.SslProtocols.Tls13)
                **.WithClientCertificates(certificates) // Missed to update the client certificate provider details**
                .Build())
            .Build());

        Console.WriteLine($"Client Connected: {mqttClient.IsConnected} with CONNACK: {connAck.ResultCode}");

        mqttClient.ApplicationMessageReceivedAsync += async m => await Console.Out.WriteAsync($"Received message on topic: '{m.ApplicationMessage.Topic}' with content: '{m.ApplicationMessage.ConvertPayloadToString()}'\n\n");

        var suback = await mqttClient.SubscribeAsync("contosotopics/topic1");
        suback.Items.ToList().ForEach(s => Console.WriteLine($"subscribed to '{s.TopicFilter.Topic}' with '{s.ResultCode}'"));

        while (true)
        {
            var puback = await mqttClient.PublishStringAsync("contosotopics/topic1", "hello world!");
            Console.WriteLine(puback.ReasonString);
            await Task.Delay(1000);
        }
    }
}