LWIP MQTT not connecting

Hi,

I'm using the STM32F746NG discovery board to connect to the thingspeak MQTT broker.

However I can't connect to the server, i'm using dns to get the server ip adres which I then use in the mqtt_client_connect function.

When I get to the callback function the status is 256 (MQTT_CONNECT_DISCONNECTED).

I've had this problem before with a local MQTT broker (mosquitto 2.0), I was able to solve this problem by installing an older version (mosquitto 1.161a).

I'm using the correct credentials because they work in the mqtt_spy application.

Has anyone had this problem before or a sollution for this problem?

With kind regards

Sébastien

Answer 1

[Vinod]

Could you provide more information - what is the client ID of your device? We may be able to look at the server logs given the client ID to provide you some pointers.

[Andrew Bierman]

I am having the same problem using lwIP to connect to mqtt3.thingspeak.com. Was there a solution to Sébastien's problem?

I too am using a dns lookup service to get the Thingspeak server ip address (54.81.146.55), and I have tested this and the conection credentials using the MQTTX client app and they work for that app.

The client ID of my device is FDolEB05DQUGNCkiJywCBAA

[Andrew Bierman]

My fault. Apparently, subscribing to a nonexistent channel casues the broker to disconnect. Without doing that it appears to work fine.