Setting UP MQTT Client on Arduino

Projects Programming
1

So I set up a mqtt broker on localhost and I can receive and send messages (checked on mac terminal as well as on node-red).
But trying in any way to set up the mqtt client on arduino fails ...

/*
 Basic MQTT example with Authentication

  - connects to an MQTT server, providing username
    and password
  - publishes "hello world" to the topic "outTopic"
  - subscribes to the topic "inTopic"
*/

#include <SPI.h>
#include <Ethernet2.h>
#include <PubSubClient.h>

// Update these with values suitable for your network.
byte mac[] = {
  0x90, 0xA2, 0xDA, 0x10, 0xB3, 0xF7
};
IPAddress ip(192, 168, 50, 109);
IPAddress myDns(192, 168, 50, 1);
IPAddress gateway(192, 168, 50, 1);
IPAddress subnet(255, 255, 255, 0);
IPAddress server(127, 0, 0, 1);

void callback(char* topic, byte* payload, unsigned int length) {
  // handle message arrived
}

EthernetClient ethClient;
PubSubClient client(server, 1883, callback, ethClient);

void setup()
{
  Ethernet.begin(mac, ip);
  // Note - the default maximum packet size is 128 bytes. If the
  // combined length of clientId, username and password exceed this,
  // you will need to increase the value of MQTT_MAX_PACKET_SIZE in
  // PubSubClient.h
  
  if (client.connect("arduinoClient", "XXX", "XXXX")) {
    client.publish("Sensors","8 °C");
    client.subscribe("ExCom");
  }
}

void loop()
{
  client.loop();
}

pw and username XXX XXXX are set up correctly !

thank you in advance

2

But trying in any way to set up the mqtt client on arduino fails ...

Some proof of that would be useful.