mqttClient.ApplicationMessageReceivedAsync could not receive the message from the server

[Mustang-666]

service
builder.Services.AddMqttServer(configure =>
{
var options = configure.WithDefaultEndpoint().Build();
var mqttFactory = new MqttFactory(new MqttConsoleLogger());
var mqttServer = mqttFactory.CreateMqttServer(options);
mqttServer.StartAsync().Wait();
mqttServer.InterceptingPublishAsync += InterceptApplicationMessagePublishAsync;
});

Task InterceptApplicationMessagePublishAsync(InterceptingPublishEventArgs args)
{
try
{
var message = args.ApplicationMessage;
var json = message.ConvertPayloadToString();

    Console.WriteLine($"Topic:{message.Topic}, TopicAlias:{message.TopicAlias}, ResponseTopic:{message.ResponseTopic}, Message：{json}");

    return Task.CompletedTask;
}
catch (Exception ex)
{
    return Task.FromException(ex);
}

}

public class HomeController : Controller
{
    private readonly ILogger<HomeController> _logger;
    private readonly MqttServer _mqtt;
    public HomeController(ILogger<HomeController> logger, MqttServer mqtt)
    {
        _logger = logger;
        _mqtt = mqtt;
    }

    public async Task<IActionResult> GetClients()
    {
        var list = await _mqtt.GetClientsAsync();
        return Json(list);
    }

    public async Task<IActionResult> Publish()
    {
        string topic = $"topictest";
        string inputMessage = $"Test application message from MQTTnet server.";

        MqttApplicationMessage application_message = new MqttApplicationMessageBuilder()
            .WithPayload(inputMessage)
            .WithTopic(topic)
            .Build();
        var message = new InjectedMqttApplicationMessage(application_message);
        await _mqtt.InjectApplicationMessage(message);

        return Json(new { DateTime = DateTime.Now, Guid = System.Guid.NewGuid().ToString() });
    }

}

client

var mqttFactory = new MqttFactory();
using (var mqttClient = mqttFactory.CreateMqttClient())
{
var mqttClientOptions = new MqttClientOptionsBuilder().WithTcpServer("127.0.0.1").Build();

mqttClient.ApplicationMessageReceivedAsync += args =>
{
    Console.WriteLine(args.ApplicationMessage.ConvertPayloadToString());
    return Task.CompletedTask;
};

await mqttClient.ConnectAsync(mqttClientOptions, CancellationToken.None);

var mqttSubscribeOptions = mqttFactory.CreateSubscribeOptionsBuilder()
           .WithTopicFilter(f => { f.WithTopic("topictest"); })
           .Build();
var response = await mqttClient.SubscribeAsync(mqttSubscribeOptions, CancellationToken.None);
Console.WriteLine("MQTT client subscribed to topic.");
Console.WriteLine("Press enter to exit.");
Console.ReadLine();

}

Where is my problem?

[Mustang-666]

        var message = new InjectedMqttApplicationMessage(application_message);
        message.SenderClientId = "ClientId123";
        await _mqtt.InjectApplicationMessage(message);


var mqttClientOptions = new MqttClientOptionsBuilder()
    .WithClientId("ClientId123")
    .WithTcpServer("127.0.0.1").Build();

Still can't get it

[HninNweAye]

@Mustang-666 I'm also encountering the same problem. Please share if you found the issue.I'm using .NET 6.0

[Jubast]

This happened to me. The issue was that the mqtt server was created / initialized multiple times.
MqttServer created -> Clients connected -> MqttServer created (previous connected clients lost) -> _mqtt.InjectApplicationMessage() to 0 connected clients.