Connecting and adding Arduino MKR NBIoT 1500 board to the cloud server - arduino

Question

I tried connecting the Arduino MKR NBIoT 1500 board to the Azure IoT Hub but wasn't successful. The board was able to connect to the cellular network and I tried to connect to Azure IoT Hub using MQTT but getting an error “-2”. I have also tried Google IoT and AWS IoT core and I'm still having the same error. I would appreciate if anyone could give me a feedback on what to do to be able to solve the problem. Thank you
Azure IoT Hub NB
This sketch securely connects to an Azure IoT Hub using MQTT over NB IoT/LTE Cat M1.
It uses a private key stored in the ATECC508A and a self signed public
certificate for SSL/TLS authetication.
It publishes a message every 5 seconds to "devices/{deviceId}/messages/events/" topic
and subscribes to messages on the "devices/{deviceId}/messages/devicebound/#"
topic.
The circuit:
- MKR NB 1500 board
- Antenna
- SIM card with a data plan
- LiPo battery
The following tutorial on Arduino Project Hub can be used
to setup your Azure account and the MKR board:
https://create.arduino.cc/projecthub/Arduino_Genuino/securely-connecting-an-arduino-nb-1500-to-azure-iot-hub-af6470
This example code is in the public domain.
*/
#include <ArduinoBearSSL.h>
#include <ArduinoECCX08.h>
#include <utility/ECCX08SelfSignedCert.h>
#include <ArduinoMqttClient.h>
#include <MKRNB.h>
#include "arduino_secrets.h"
/////// Enter your sensitive data in arduino_secrets.h
const char pinnumber[] = SECRET_PINNUMBER;
const char broker[] = SECRET_BROKER;
String deviceId = SECRET_DEVICE_ID;
NB nbAccess=true;
GPRS gprs;
NBClient nbClient; // Used for the TCP socket connection
BearSSLClient sslClient(nbClient); // Used for SSL/TLS connection, integrates with ECC508
MqttClient mqttClient(sslClient);
unsigned long lastMillis = 0;
void setup() {
Serial.begin(9600);
while (!Serial);
if (!ECCX08.begin()) {
Serial.println("No ECCX08 present!");
while (1);
}
// reconstruct the self signed cert
ECCX08SelfSignedCert.beginReconstruction(0, 8);
ECCX08SelfSignedCert.setCommonName(ECCX08.serialNumber());
ECCX08SelfSignedCert.endReconstruction();
// Set a callback to get the current time
// used to validate the servers certificate
ArduinoBearSSL.onGetTime(getTime);
// Set the ECCX08 slot to use for the private key
// and the accompanying public certificate for it
sslClient.setEccSlot(0, ECCX08SelfSignedCert.bytes(), ECCX08SelfSignedCert.length());
// Set the client id used for MQTT as the device id
mqttClient.setId(deviceId);
// Set the username to "<broker>/<device id>/api-version=2018-06-30" and empty password
String username;
username += broker;
username += "/";
username += deviceId;
username += "/api-version=2018-06-30";
mqttClient.setUsernamePassword(username, "");
// Set the message callback, this function is
// called when the MQTTClient receives a message
mqttClient.onMessage(onMessageReceived);
}
void loop() {
if (nbAccess.status() != NB_READY || gprs.status() != GPRS_READY) {
connectNB();
}
if (!mqttClient.connected()) {
// MQTT client is disconnected, connect
connectMQTT();
}
// poll for new MQTT messages and send keep alives
mqttClient.poll();
// publish a message roughly every 5 seconds.
if (millis() - lastMillis > 5000) {
lastMillis = millis();
publishMessage();
}
}
unsigned long getTime() {
// get the current time from the cellular module
return nbAccess.getTime();
//return 1583929365;
}
void connectNB() {
Serial.println("Attempting to connect to the cellular network");
while ((nbAccess.begin(pinnumber) != NB_READY) ||
(gprs.attachGPRS() != GPRS_READY)) {
// failed, retry
Serial.print(".");
delay(1000);
}
Serial.println("You're connected to the cellular network");
Serial.println();
}
void connectMQTT() {
Serial.print("Attempting to MQTT broker: ");
Serial.print(broker);
Serial.println(" ");
while (!mqttClient.connect(broker, 8883)) {
// failed, retry
Serial.print(".");
Serial.println(mqttClient.connectError());
delay(5000);
}
Serial.println();
Serial.println("You're connected to the MQTT broker");
Serial.println();
// subscribe to a topic
mqttClient.subscribe("devices/" + deviceId + "/messages/devicebound/#");
}
void publishMessage() {
Serial.println("Publishing message");
// send message, the Print interface can be used to set the message contents
mqttClient.beginMessage("devices/" + deviceId + "/messages/events/");
mqttClient.print("hello ");
mqttClient.print(millis());
mqttClient.endMessage();
}
void onMessageReceived(int messageSize) {
// we received a message, print out the topic and contents
Serial.print("Received a message with topic '");
Serial.print(mqttClient.messageTopic());
Serial.print("', length ");
Serial.print(messageSize);
Serial.println(" bytes:");
// use the Stream interface to print the contents
while (mqttClient.available()) {
Serial.print((char)mqttClient.read());
}
Serial.println();
Serial.println();
}
// NB settings
#define SECRET_PINNUMBER ""
// Fill in the hostname of your Azure IoT Hub broker
#define SECRET_BROKER "ArduinoProjectHub.azure-devices.net"
// Fill in the device id
#define SECRET_DEVICE_ID "MKRNB1500"