using MQTTnet;
using MQTTnet.Client;
using MQTTnet.Client.Connecting;
using MQTTnet.Client.Options;
using MQTTnet.Client.Publishing;
using MQTTnet.Internal;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Xamarin.Essentials;
using XSales.Maps.Mobile.Global;
using XSales.Maps.Mobile.Models;
namespace XSales.Maps.Mobile.Mqtt 
    public class MQTTclient
        private IMqttClientOptions manageClientOptions;
        public IMqttClient mqttClient;
        private IMqttClientOptions clientOptions;
        // Create a new MQTT client.
        private MqttFactory factory;
        private static string clientId = "03cb09bf-0d04-4228-8b71-b87ed10e7492";
        bool mqttSecure = false;
        public Action<MqttClientConnectedEventArgs> mqttActionConnected;
        public Action<MqttApplicationMessageReceivedEventArgs> mqttMessageReceived;
        public MQTTclient(string url)
            factory = new MqttFactory();
            mqttClient = factory.CreateMqttClient();
            var site = url.Split(':');
            var uri = site[0];
            var port = Int32.Parse(site[1]);
            clientOptions = new MqttClientOptionsBuilder()
                .WithClientId(clientId)
                .WithCommunicationTimeout(new TimeSpan(0,30,0))
                .WithTcpServer(uri, port)
                .WithCleanSession()
                .Build();
        public void ConnectClientAsync()
            if (!mqttClient.IsConnected)
                mqttClient.UseDisconnectedHandler(e =>
                    Util.Log(Util.LogType.Debug, MethodBase.GetCurrentMethod(), JsonConvert.SerializeObject(e));
                    Util.Log(Util.LogType.Debug, MethodBase.GetCurrentMethod(), "### DISCONNECTED FROM SERVER ###");
                });
                mqttClient.UseConnectedHandler(async e =>
                    Util.Log(Util.LogType.Information, MethodBase.GetCurrentMethod(), "### CONNECTED WITH SERVER ###");
                    // Subscribe to a topic
                    await mqttClient.SubscribeAsync(new TopicFilterBuilder().WithTopic("topic/tracking").Build());
                    Util.Log(Util.LogType.Debug, MethodBase.GetCurrentMethod(), "### SUBSCRIBED ###");




    

                });
                //mqttClient.UseApplicationMessageReceivedHandler(e =>
                //    Console.WriteLine("### RECEIVED APPLICATION MESSAGE ###");
                //    Console.WriteLine($"+ Topic = {e.ApplicationMessage.Topic}");
                //    Console.WriteLine($"+ Payload = {Encoding.UTF8.GetString(e.ApplicationMessage.Payload)}");
                //    Console.WriteLine();
                //});
                mqttClient.UseApplicationMessageReceivedHandler(mqttMessageReceived);
                mqttClient.ConnectAsync(clientOptions, CancellationToken.None).Wait();
        public async Task ClientDisconnect()
            await mqttClient.DisconnectAsync();
        public async Task PublishAsync(string topic, string payload, bool retainFlag = true, int qos = 2)
            if (mqttClient.IsConnected)
                    var message = new MqttApplicationMessageBuilder()
                                .WithTopic(topic)
                                .WithPayload(payload)
                                .WithQualityOfServiceLevel(MQTTnet.Protocol.MqttQualityOfServiceLevel.ExactlyOnce)
                                .WithRetainFlag(retainFlag)
                                .Build();
                    Util.Log(Util.LogType.Debug, MethodBase.GetCurrentMethod(),$"### SENDING MESSAGE TO SERVER ### {payload}");
                    await mqttClient.PublishAsync(message, CancellationToken.None);
                    return;
                catch (TaskCanceledException tce)
                    Util.Log(Util.LogType.Debug, MethodBase.GetCurrentMethod(), $"Task Cancelled: {tce.Message}");
                    return;
                catch (Exception ex)
                    Util.Log(Util.LogType.Debug, MethodBase.GetCurrentMethod(), $"No: {ex.Message} | {ex.Source}");
                    return;
And this is the method I use to send the data.
        public async Task SendDataMqtt(MqttDataType mqttDataType, object oPayload)
            var m = MethodBase.GetCurrentMethod();
            var dataTask = App.Database.GetDataAsync();
            var data = dataTask.Result;
            switch (mqttDataType)
                case MqttDataType.Tracking:
                    var coordinate = (Coord)oPayload;
                    if (coordinate != null)
                        Log(LogType.Debug, m, $"Creating header object to send");
                        Log(LogType.Debug, m, $"Creating MQTT Client");
                        var mqtt = new MQTTclient(data.hostname);
                        mqtt.mqttMessageReceived = e =>
                            Console.WriteLine("### RECEIVED APPLICATION MESSAGE ###");
                            Console.WriteLine($"+ Topic = {e.ApplicationMessage.Topic}");
                            Console.WriteLine($"+ Payload = {Encoding.UTF8.GetString(e.ApplicationMessage.Payload)}");
                            Console.WriteLine();
                        mqtt.ConnectClientAsync();
                        var header = new List<Header>();
                        header.Add(new Header
                            order = 1,
                            key = "reference",
                            label = "",
                            value = $"{data.ownCode}-{data.ownName} {DateTime.Now}"
                        });
                        Log(LogType.Debug, m, $"Creating MQTT Payload");
                        var payload = new MqttPayload()
                            user = data.email,
                            latitude = coordinate.latitude,
                            longitude = coordinate.longitude,
                            date = coordinate.date.ToString("yyyy-MM-dd HH:mm:ss"),
                            token = data.token,
                            header = header
                        Log(LogType.Debug, m, $"Trying to publish PAYLOAD coordinates in MQTT");
                        await mqtt.PublishAsync("topic/tracking", JsonConvert.SerializeObject(payload));
                        Log(LogType.Debug, m, $"Coordinate Published");
                        //coord.sent = true;
                        //App.Database.UpdateCoordAsync(coord);
                        await mqtt.ClientDisconnect();
                    break;
          
Please try with QoS 0 and 1 (just for testing). Also please change "Wait" and "Result" calls to proper "await" ones.
Apart from that the code looks OK to me. I assume it is a problem with async/await and Xamarin. So nothing which is located in this lib directly. I also have a Xamarin project which uses this lib and it works without problems (latest version of MQTTnet).