MQTTnet PublishAsync异常

Question

我正在尝试在Xamarin应用程序中使用"MQTTnet“。它连接得很好，但是当我尝试发布任何东西时，它会发布，但大约5秒后，它就会抛出以下异常

MQTTnet.Exceptions.MqttCommunicationTimedOutException

我不太确定那里发生了什么，服务器成功地接收到了消息

Server auth xmr/47cd7021-0f32-4cd4-b549-e8ebce2df612 from 192.168.1.8
Client xmr/47cd7021-0f32-4cd4-b549-e8ebce2df612 connected
Total connections: 3
$SYS/POezxDu/new/clients xmr/47cd7021-0f32-4cd4-b549-e8ebce2df612
hello/world hey
Client xmr/47cd7021-0f32-4cd4-b549-e8ebce2df612 disconnected
Total connections: 2
$SYS/POezxDu/disconnect/clients xmr/47cd7021-0f32-4cd4-b549-e8ebce2df612

代码如下：

using System;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
using MQTTnet;
using MQTTnet.Client;
using MQTTnet.Client.Options;
using System.Threading;

namespace MQTTXamarin
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class Login : ContentPage
    {
        public Login()
        {
            InitializeComponent();
        }

        private void Btn_Login_Clicked(object sender, EventArgs e)
        {
            MqttConnect();  
        }

        /* MQTT */
        readonly IMqttClient client = new MqttFactory().CreateMqttClient();
        private async void MqttConnect()
        {
            var options = new MqttClientOptionsBuilder()
                .WithClientId("xmr/" + Guid.NewGuid().ToString())
                .WithTcpServer("192.168.1.200", 1883)
                .WithCredentials("DyPFunIOcljUT51i", "K1YMeKkvrK6yMvm7IlHadBA6JDBKzPGc")
                .Build();
            await client.ConnectAsync(options, CancellationToken.None);
            var message = new MqttApplicationMessageBuilder()
                .WithTopic("hello/world")
                .WithPayload("hey")
                .WithExactlyOnceQoS()
                .Build();
            await client.PublishAsync(message, CancellationToken.None);
        }

    }
}

是我做错了什么呢，还是这有问题？

Answer 1

此问题已通过更改

.WithExactlyOnceQoS()

至

.WithAtLeastOnceQoS()