ESP32 lwmqtt_network_failed_connect

[Heath]

@Wayne_Hughes & @Justin_Decker,

I did some digging this morning and have found a potential solution. Here’s the updated code:

/**
 * Example that connects an ESP32 based board to the Losant
 * IoT platform. This example reports state to Losant whenever a button is
 * pressed. It also listens for the "toggle" command to turn the LED on and off.
 *
 * This example assumes the following connections:
 * Button connected to pin 14.
 * LED connected to pin 12.
 *
 * Copyright (c) 2021 Losant. All rights reserved.
 * http://losant.com
 */

#include <WiFiClientSecure.h>
#include <Losant.h>

// WiFi credentials.
const char* WIFI_SSID = "";
const char* WIFI_PASS = "";

// Losant credentials.
const char* LOSANT_DEVICE_ID = "";
const char* LOSANT_ACCESS_KEY = "";
const char* LOSANT_ACCESS_SECRET = "";

const int BUTTON_PIN = 14;
const int LED_PIN = 12;

bool ledState = false;

const char* rootCABuff = \
"-----BEGIN CERTIFICATE-----\n" \
"MIIDrzCCApegAwIBAgIQCDvgVpBCRrGhdWrJWZHHSjANBgkqhkiG9w0BAQUFADBh\n" \
"MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3\n" \
"d3cuZGlnaWNlcnQuY29tMSAwHgYDVQQDExdEaWdpQ2VydCBHbG9iYWwgUm9vdCBD\n" \
"QTAeFw0wNjExMTAwMDAwMDBaFw0zMTExMTAwMDAwMDBaMGExCzAJBgNVBAYTAlVT\n" \
"MRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5j\n" \
"b20xIDAeBgNVBAMTF0RpZ2lDZXJ0IEdsb2JhbCBSb290IENBMIIBIjANBgkqhkiG\n" \
"9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4jvhEXLeqKTTo1eqUKKPC3eQyaKl7hLOllsB\n" \
"CSDMAZOnTjC3U/dDxGkAV53ijSLdhwZAAIEJzs4bg7/fzTtxRuLWZscFs3YnFo97\n" \
"nh6Vfe63SKMI2tavegw5BmV/Sl0fvBf4q77uKNd0f3p4mVmFaG5cIzJLv07A6Fpt\n" \
"43C/dxC//AH2hdmoRBBYMql1GNXRor5H4idq9Joz+EkIYIvUX7Q6hL+hqkpMfT7P\n" \
"T19sdl6gSzeRntwi5m3OFBqOasv+zbMUZBfHWymeMr/y7vrTC0LUq7dBMtoM1O/4\n" \
"gdW7jVg/tRvoSSiicNoxBN33shbyTApOB6jtSj1etX+jkMOvJwIDAQABo2MwYTAO\n" \
"BgNVHQ8BAf8EBAMCAYYwDwYDVR0TAQH/BAUwAwEB/zAdBgNVHQ4EFgQUA95QNVbR\n" \
"TLtm8KPiGxvDl7I90VUwHwYDVR0jBBgwFoAUA95QNVbRTLtm8KPiGxvDl7I90VUw\n" \
"DQYJKoZIhvcNAQEFBQADggEBAMucN6pIExIK+t1EnE9SsPTfrgT1eXkIoyQY/Esr\n" \
"hMAtudXH/vTBH1jLuG2cenTnmCmrEbXjcKChzUyImZOMkXDiqw8cvpOp/2PV5Adg\n" \
"06O/nVsJ8dWO41P0jmP6P6fbtGbfYmbW0W5BjfIttep3Sp+dWOIrWcBAI+0tKIJF\n" \
"PnlUkiaY4IBIqDfv8NZ5YBberOgOzW6sRBc4L0na4UU+Krk2U886UAb3LujEV0ls\n" \
"YSEY1QSteDwsOoBrp+uvFRTp2InBuThs4pFsiv9kuXclVzDAGySj4dzp30d8tbQk\n" \
"CAUw7C29C79Fv1C5qfPrmAESrciIxpg0X40KPMbp1ZWVbd4=\n" \
"-----END CERTIFICATE-----\n";

// initiate the the wifi client
WiFiClientSecure wifiClient;

LosantDevice device(LOSANT_DEVICE_ID);

void toggle() {
  Serial.println("Toggling LED.");
  ledState = !ledState;
  digitalWrite(LED_PIN, ledState ? HIGH : LOW);
}

// Called whenever the device receives a command from the Losant platform.
void handleCommand(LosantCommand *command) {
  Serial.print("Command received: ");
  Serial.println(command->name);

  // Optional command payload. May not be present on all commands.
  // JsonObject payload = *command->payload;

  // Perform action specific to the command received.
  if(strcmp(command->name, "toggle") == 0) {
    toggle();
    /**
    * In Losant, including a payload along with your
    * command is optional. This is an example of how
    * to parse a JSON payload from Losant and print
    * the value of a key called "temperature".
    */
    // int temperature = payload["temperature"];
    // Serial.println(temperature);
  }
}

void connect() {

  // Connect to Wifi.
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(WIFI_SSID);

//  wifiClient.setInsecure();

  WiFi.begin(WIFI_SSID, WIFI_PASS);
  wifiClient.setCACert(rootCABuff);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }  

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

  // Connect to Losant.
  Serial.println();
  Serial.print("Connecting to Losant...");

  device.connectSecure(wifiClient, LOSANT_ACCESS_KEY, LOSANT_ACCESS_SECRET);

  while(!device.connected()) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("Connected!");
}

void setup() {
  Serial.begin(115200);
  while(!Serial) { }
  pinMode(BUTTON_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);

  // Register the command handler to be called when a command is received
  // from the Losant platform.
  device.onCommand(&handleCommand);

  connect();
}

void buttonPressed() {
  Serial.println("Button Pressed!");

  // Losant uses a JSON protocol. Construct the simple state object.
  // { "button" : true }
  StaticJsonDocument<200> jsonBuffer;
  JsonObject root = jsonBuffer.to<JsonObject>();
  root["button"] = true;

  // Send the state to Losant.
  device.sendState(root);
}

int buttonState = 0;

void loop() {

  bool toReconnect = false;

  if(WiFi.status() != WL_CONNECTED) {
    Serial.println("Disconnected from WiFi");
    toReconnect = true;
  }

  if(!device.connected()) {
    Serial.println("Disconnected from Losant");
    toReconnect = true;
  }

  if(toReconnect) {
    connect();
  }

  device.loop();

  int currentRead = digitalRead(BUTTON_PIN);

  if(currentRead != buttonState) {
    buttonState = currentRead;
    if(buttonState) {
      buttonPressed();
    }
  }

  delay(100);
}

What I was able to find is that prior to 2019, the root CA that Losant’s certificate chained down to came on the ESP32 by default. In 2019, some changes were made and that was no longer the case. Now, to use a secure connection to Losant, you either need to set the root CA on the device, or not verify the certificate coming from the server (not really that secure).

I will be updating the official example in our code today so that this does not happen again in the future.

Please let me know if this works for you, or if you run into any other roadblocks.

Thank you,
Heath