How to connect to an MQTTServer in a Blazor app published to IIS?

Question

Trying to get over this bump to begin getting my Home Automation projects going.

• I created a Blazor Server App using the template in VS 2022.
• Added a menu item called "Lights" that brings up a Lights.razor page.
• In it, I added the below MQTTServer code:

@code {
    protected override void OnInitialized()
    {
        MQTTService.MQTTServer_Start();
    }

    async void MQTTServer_Start()
    {
        var options = new MqttServerOptionsBuilder().WithDefaultEndpoint().WithDefaultEndpointPort(1111);
        var server = new MqttFactory().CreateMqttServer(options.Build());
        server.InterceptingPublishAsync += Server_InterceptingPublishAsync;
        await server.StartAsync();
        Task Server_InterceptingPublishAsync(InterceptingPublishEventArgs arg)
        {
            var payload = arg.ApplicationMessage?.Payload == null ? null : Encoding.UTF8.GetString(arg.ApplicationMessage?.Payload);
            Debug.WriteLine(arg.ClientId);
            return Task.CompletedTask;
        }
    }
}

• I hit run. It seems to launch its own web server, likely IISExpress; not sure.
• The Blazor template web site comes up fine.
• I click the Lights menu item I added, the Light page comes up fine.
• The page runs MQTTServer as per the above code.
• I run my MicroPython MQTTClient code from my Raspberry Pico W and successfully connect with that MQTTServer.
• I stop the Blazor app.
• I publish it to my IIS Server on this same machine.
• I goto that IIS Hosted Blazor app with Chrome.
• Click on the Lights menu item.
• I run my MicroPython MQTTClient code from my Raspberry Pico W and it fails with the error: "Traceback (most recent call last): File "umqttsimple.py", line 61, in connect OSError: [Errno 103] ECONNABORTED"

Anyone has any idea why it works from VS but fails from IIS? Any good techniques out there I could follow to get over that bump?

Answer 1

Fixed by creating both an inbound and outbound Firewall rule for the Port allowing access. However this doesn't explain it is not needed when the same code and web site are run by Visual Studio compared to when it's running in IIS; on the same machine. I'll consider posting that as a separate question on here.