Hello, First, I need more detail. Can you provide your code?

Second, I provide a Github repository that helps you

behrooz bozorg chami

This's my code.

using System; using System.Threading; using System.Threading.Tasks; using MQTTnet.Server; using MQTTnet; using System.Text; using static System.Console;

namespace MqttBroker { class Program { static void Main(string[] args) {

        // Create the options for MQTT Broker
        var options = new MqttServerOptionsBuilder()
            //Set endpoint to localhost
            .WithDefaultEndpoint();
        // Create a new mqtt server
        var server = new MqttFactory().CreateMqttServer(options.Build());
        //Add Interceptor for logging incoming messages
        server.InterceptingPublishAsync += Server_InterceptingPublishAsync;

        // Start the server
        //await server.StartAsync();

        server.StartAsync();

        // Keep application running until user press a key
        ReadLine();

        Task Server_InterceptingPublishAsync(InterceptingPublishEventArgs arg)
        {
            // Convert Payload to string
            var payload = arg.ApplicationMessage?.Payload == null ? null : Encoding.UTF8.GetString(arg.ApplicationMessage?.Payload);


            WriteLine(
                " TimeStamp: {0} -- Message: ClientId = {1}, Topic = {2}, Payload = {3}, QoS = {4}, Retain-Flag = {5}",

                DateTime.Now,
                arg.ClientId,
                arg.ApplicationMessage?.Topic,
                payload,
                arg.ApplicationMessage?.QualityOfServiceLevel,
                arg.ApplicationMessage?.Retain);
            return Task.CompletedTask;
        }
    }
}

If I did comment out "//await server.StartAsync();" and used server.StartAsync(); it's ok.

So,let me know solution,and also I am waiting for MQTT broker with username/password authenticated from clients request.