Library getting crashed / looped on last mile network disconnect

[pprakash]

Hi @khoih-prog

Have been learning ESP series of controllers with MQTT. Thanks for this wonderful stack of libraries which enabled me to learn Async communications and MQTT.

Recently I stumbled on an issue with AsyncMqtt_Generic library. I tested version 1.6.1, 1.7.0 & 1.8.0 with SSL enabled. Have faced similar issue with all these versions.

Issue Description
After mqtt client connects to the server, if publish is attempted when there is a last mile disconnect on communication between the server and client, the connection doesn't recover when the network comes back.

How to Simulate the Scenario
Step 1: Configure Mqtt Client with SSL and connect to the MQTT Server
Step 2: Similar a network failure ( I pulled of the WAN cable from the router)
Step 3: Wait until the Mqtt Client times out and disconnects
Step 4: Send multiple Publish to the server
Step 5: Re-establish the network.

Platform:
ESP32-WROOM-32 Module
PLATFORM: Espressif 32 (5.3.0) > Espressif ESP32 Dev Module
HARDWARE: ESP32 240MHz, 320KB RAM, 4MB Flash

• framework-arduinoespressif32 @ 3.20006.221224 (2.0.6)
• tool-esptoolpy @ 1.40400.0 (4.4.0)
• tool-mkfatfs @ 2.0.1
• tool-mklittlefs @ 1.203.210628 (2.3)
• tool-mkspiffs @ 2.230.0 (2.30)
• toolchain-xtensa-esp32 @ 8.4.0+2021r2-patch5

Sketch
This is FullyFeaturedSSL_ESP32 will little modification.

/****************************************************************************************************************************
  FullyFeatureSSL_ESP32.ino

  AsyncMqttClient_Generic is a library for ESP32, ESP8266, Protenta_H7, STM32F7, etc. with current AsyncTCP support

  Based on and modified from :

  1) async-mqtt-client (https://github.com/marvinroger/async-mqtt-client)

  Built by Khoi Hoang https://github.com/khoih-prog/AsyncMqttClient_Generic
 *****************************************************************************************************************************/

// Example project which can be built with SSL enabled or disabled.
// The espressif8266_stage platform must be installed.
// Refer to platformio.ini for the build configuration and platform installation.

#include "defines.h"

#include <WiFi.h>

extern "C"
{
#include "freertos/FreeRTOS.h"
#include "freertos/timers.h"
}

#define ASYNC_TCP_SSL_ENABLED       true
//#define ASYNC_TCP_SSL_ENABLED       false

#include <AsyncMqtt_Generic.h>

//#define MQTT_HOST         IPAddress(192, 168, 2, 110)
#define MQTT_HOST         "broker.emqx.io"        // Broker address

#if ASYNC_TCP_SSL_ENABLED

#define MQTT_SECURE     true

const uint8_t MQTT_SERVER_FINGERPRINT[] = {0x7e, 0x36, 0x22, 0x01, 0xf9, 0x7e, 0x99, 0x2f, 0xc5, 0xdb, 0x3d, 0xbe, 0xac, 0x48, 0x67, 0x5b, 0x5d, 0x47, 0x94, 0xd2};
const char *PubTopic  = "async-mqtt/ESP32_SSL_Pub";               // Topic to publish

#define MQTT_PORT       8883

#else

const char *PubTopic  = "async-mqtt/ESP32_Pub";                   // Topic to publish

#define MQTT_PORT       1883

#endif

AsyncMqttClient mqttClient;
TimerHandle_t mqttReconnectTimer;
TimerHandle_t wifiReconnectTimer;

void connectToWifi()
{
  Serial.println("Connecting to Wi-Fi...");
  WiFi.begin(__WIFI_SSID, __WIFI_PASSWORD);
}

void connectToMqtt()
{
  Serial.println("Connecting to MQTT...");
  mqttClient.connect();
}

void WiFiEvent(WiFiEvent_t event)
{
  switch (event)
  {
#if USING_CORE_ESP32_CORE_V200_PLUS

    case ARDUINO_EVENT_WIFI_READY:
      Serial.println("WiFi ready");
      break;

    case ARDUINO_EVENT_WIFI_STA_START:
      Serial.println("WiFi STA starting");
      break;

    case ARDUINO_EVENT_WIFI_STA_CONNECTED:
      Serial.println("WiFi STA connected");
      break;

    case ARDUINO_EVENT_WIFI_STA_GOT_IP6:
    case ARDUINO_EVENT_WIFI_STA_GOT_IP:
      Serial.println("WiFi connected");
      Serial.print("IP address: ");
      Serial.println(WiFi.localIP());
      connectToMqtt();
      break;

    case ARDUINO_EVENT_WIFI_STA_LOST_IP:
      Serial.println("WiFi lost IP");
      break;

    case ARDUINO_EVENT_WIFI_STA_DISCONNECTED:
      Serial.println("WiFi lost connection");
      xTimerStop(mqttReconnectTimer, 0); // ensure we don't reconnect to MQTT while reconnecting to Wi-Fi
      xTimerStart(wifiReconnectTimer, 0);
      break;
#else

    case SYSTEM_EVENT_STA_GOT_IP:
      Serial.println("WiFi connected");
      Serial.println("IP address: ");
      Serial.println(WiFi.localIP());
      connectToMqtt();
      break;

    case SYSTEM_EVENT_STA_DISCONNECTED:
      Serial.println("WiFi lost connection");
      xTimerStop(mqttReconnectTimer, 0); // ensure we don't reconnect to MQTT while reconnecting to Wi-Fi
      xTimerStart(wifiReconnectTimer, 0);
      break;
#endif

    default:
      break;
  }
}

void printSeparationLine()
{
  Serial.println("************************************************");
}

void onMqttConnect(bool sessionPresent)
{
  Serial.print("Connected to MQTT broker: ");
  Serial.print(MQTT_HOST);
  Serial.print(", port: ");
  Serial.println(MQTT_PORT);
  Serial.print("PubTopic: ");
  Serial.println(PubTopic);

  printSeparationLine();
  Serial.print("Session present: ");
  Serial.println(sessionPresent);

  uint16_t packetIdSub = mqttClient.subscribe(PubTopic, 2);
  Serial.print("Subscribing at QoS 2, packetId: ");
  Serial.println(packetIdSub);

  mqttClient.publish(PubTopic, 0, true, "ESP32 Test");
  Serial.println("Publishing at QoS 0");

  uint16_t packetIdPub1 = mqttClient.publish(PubTopic, 1, true, "test 2");
  Serial.print("Publishing at QoS 1, packetId: ");
  Serial.println(packetIdPub1);

  uint16_t packetIdPub2 = mqttClient.publish(PubTopic, 2, true, "test 3");
  Serial.print("Publishing at QoS 2, packetId: ");
  Serial.println(packetIdPub2);

  printSeparationLine();
}

void onMqttDisconnect(AsyncMqttClientDisconnectReason reason)
{
  (void) reason;

  Serial.println("#################### Disconnected from MQTT.###########################");

  if (WiFi.isConnected())
  {
    xTimerStart(mqttReconnectTimer, 0);
  }
}

void onMqttSubscribe(const uint16_t& packetId, const uint8_t& qos)
{
  Serial.println("Subscribe acknowledged.");
  Serial.print("  packetId: ");
  Serial.println(packetId);
  Serial.print("  qos: ");
  Serial.println(qos);
}

void onMqttUnsubscribe(const uint16_t& packetId)
{
  Serial.println("Unsubscribe acknowledged.");
  Serial.print("  packetId: ");
  Serial.println(packetId);
}

void onMqttMessage(char* topic, char* payload, const AsyncMqttClientMessageProperties& properties,
                   const size_t& len, const size_t& index, const size_t& total)
{
  (void) payload;

  Serial.println("Publish received.");
  Serial.print("  topic: ");
  Serial.println(topic);
  Serial.print("  qos: ");
  Serial.println(properties.qos);
  Serial.print("  dup: ");
  Serial.println(properties.dup);
  Serial.print("  retain: ");
  Serial.println(properties.retain);
  Serial.print("  len: ");
  Serial.println(len);
  Serial.print("  index: ");
  Serial.println(index);
  Serial.print("  total: ");
  Serial.println(total);
}

void onMqttPublish(const uint16_t& packetId)
{
  Serial.println("Publish acknowledged");
  Serial.print("  packetId: ");
  Serial.println(packetId);
}

void setup()
{
  Serial.begin(115200);

  while (!Serial && millis() < 5000);

  Serial.print("\nStarting FullyFeatureSSL_ESP32 on ");
  Serial.println(ARDUINO_BOARD);
  Serial.println(ASYNC_MQTT_GENERIC_VERSION);

  mqttReconnectTimer = xTimerCreate("mqttTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0,
                                    reinterpret_cast<TimerCallbackFunction_t>(connectToMqtt));
  wifiReconnectTimer = xTimerCreate("wifiTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0,
                                    reinterpret_cast<TimerCallbackFunction_t>(connectToWifi));

  WiFi.onEvent(WiFiEvent);

  mqttClient.onConnect(onMqttConnect);
  mqttClient.onDisconnect(onMqttDisconnect);
  mqttClient.onSubscribe(onMqttSubscribe);
  mqttClient.onUnsubscribe(onMqttUnsubscribe);
  mqttClient.onMessage(onMqttMessage);
  mqttClient.onPublish(onMqttPublish);

  mqttClient.setServer(MQTT_HOST, MQTT_PORT);

#if ASYNC_TCP_SSL_ENABLED
  mqttClient.setSecure(MQTT_SECURE);

  if (MQTT_SECURE)
  {
    //mqttClient.addServerFingerprint((const uint8_t[])MQTT_SERVER_FINGERPRINT);
    mqttClient.addServerFingerprint((const uint8_t *)MQTT_SERVER_FINGERPRINT);
  }

#endif

  connectToWifi();
}

void loop()
{
  uint16_t packetIdPub1 = mqttClient.publish(PubTopic, 1, true, "test 2");
  Serial.print("Publishing at QoS 1, packetId: ");
  delay(2000);
}

Logs with MQTT Debug Enabled

[AMQTT] _addBack: new back, packetType = PUBLISH
#################### Disconnected from MQTT.###########################
Publishing at QoS 1, packetId: Connecting to MQTT...
[AMQTT] CONNECTING
[AMQTT] ClientID = esp32-d0890355b594
[AMQTT] _onDisconnect: TCP disconn
Publishing at QoS 1, packetId: Publishing at QoS 1, packetId: Publishing at QoS 1, packetId: E (119162) task_wdt: Task watchdog got triggered. The following tasks did not reset the watchdog in time:
E (119162) task_wdt:  - async_tcp_ssl (CPU 0/1)
E (119162) task_wdt: Tasks currently running:
E (119162) task_wdt: CPU 0: wifi
E (119162) task_wdt: CPU 1: IDLE
E (119162) task_wdt: Aborting.

abort() was called at PC 0x400e6055 on core 0


Backtrace: 0x40083705:0x3ffbed4c |<-CORRUPTED

Logs with ATCP & MQTT Debug Enabled

[ATCP] _poll: NULL pcb
[ATCP] _tcp_connected: pcb = 0x3FFCFCC8
[ATCP] _handle_async_event: Task Name =  async_tcp_ssl
[ATCP] _handle_async_event: LWIP_TCP_CONNECTED = 0x3FFC3FE8 0x3FFCFCC8
[ATCP] _handle_async_event: LWIP_TCP_CONNECTED =  0
[ATCP] _tcp_sent: pcb = 0x3FFCFCC8
[ATCP] [ATCP] _tcp_recv: pcb = 0x3FFCFCC8
_handle_async_event: Task Name =  async_tcp_ssl
[ATCP] _handle_async_event: LWIP_TCP_SENT = 0x[ATCP] _tcp_recv: pcb = 0x3FFCFCC8
3FFCFCC8
[ATCP] _sent: len = 301
[AMQTT] _onAck: ack len = 301
[ATCP] [ATCP] _tcp_recv: pcb =add() done, tcp_ssl_write size = 0x 3FFCFCC8-26880

[AMQTT] _onDisconnect: TCP disconn
Publishing at QoS 1, packetId: Publishing at QoS 1, packetId: Publishing at QoS 1, packetId: E (84905) task_wdt: Task watchdog got triggered. The following tasks did not reset the watchdog in time:
E (84905) task_wdt:  - async_tcp_ssl (CPU 0/1)
E (84905) task_wdt: Tasks currently running:
E (84905) task_wdt: CPU 0: IDLE
E (84905) task_wdt: CPU 1: IDLE
E (84905) task_wdt: Aborting.

abort() was called at PC 0x400e66ad on core 0


Backtrace: 0x40083705:0x3ffbed4c |<-CORRUPTED

In the above test scenerios it crashed both the times. But in some situations the task goes into forever loop and below log is generated on ATCP.

[AMQTT] CONNECTING
[AMQTT] ClientID = esp32-d0890355b594
[ATCP] _start_async_task init:
[ATCP] _async_queue: xQueue exists...
[ATCP] _async_service_task create:
[ATCP] _async_service_task create: OK
[ATCP] _start_async_task init:
[ATCP] _async_queue: xQueue exists...
[ATCP] _async_service_task create:
[ATCP] _async_service_task create: OK
[ATCP] _tcp_connected: pcb = 0x3FFEFF2C
[ATCP] _tcp_poll: pcb = 0x3FFEFF2C
[ATCP] _send_async_event called:
[ATCP] _send_async_event val =  1
[ATCP] _tcp_poll: pcb = 0x3FFEFF2C
[ATCP] _send_async_event called:
[ATCP] _send_async_event val =  1
[ATCP] _tcp_poll: pcb = 0x3FFEFF2C
[ATCP] _send_async_event called:
[ATCP] _send_async_event val =  1
[ATCP] _tcp_poll: pcb = 0x3FFEFF2C
[ATCP] _send_async_event called:
[ATCP] _send_async_event val =  1
[ATCP] _tcp_poll: pcb = 0x3FFEFF2C
[ATCP] _send_async_event called:
[ATCP] _send_async_event val =  1
[ATCP] _tcp_poll: pcb = 0x3FFEFF2C
[ATCP] _send_async_event called:
[ATCP] _send_async_event val =  1
[ATCP] _tcp_poll: pcb = 0x3FFEFF2C
[ATCP] _send_async_event called:
[ATCP] _send_async_event val =  1
[ATCP] _tcp_poll: pcb = 0x3FFEFF2C
[ATCP] _send_async_event called:
[ATCP] _send_async_event val =  1
[ATCP] _tcp_poll: pcb = 0x3FFEFF2C

Please let me know if you need any additional information for deep diving into this?

[khoih-prog]

Hi @pprakash

You have to know and understand when to publish to MQTT, don't blindly send when not connected to MQTT Server

That's why you have to publish only after onMqttConnect() or create a MQTT-connected status to allow publish.

The example is just simple example, to adapt to your special or extreme use-cases, you have to fully understand all the features / caveats.

AsyncMQTT_Generic/examples/ESP32/FullyFeaturedSSL_ESP32/FullyFeaturedSSL_ESP32.ino

Lines 129 to 158 in fdf0c2a

	void onMqttConnect(bool sessionPresent)
	{
	Serial.print("Connected to MQTT broker: ");
	Serial.print(MQTT_HOST);
	Serial.print(", port: ");
	Serial.println(MQTT_PORT);
	Serial.print("PubTopic: ");
	Serial.println(PubTopic);
	printSeparationLine();
	Serial.print("Session present: ");
	Serial.println(sessionPresent);
	uint16_t packetIdSub = mqttClient.subscribe(PubTopic, 2);
	Serial.print("Subscribing at QoS 2, packetId: ");
	Serial.println(packetIdSub);
	mqttClient.publish(PubTopic, 0, true, "ESP32 Test");
	Serial.println("Publishing at QoS 0");
	uint16_t packetIdPub1 = mqttClient.publish(PubTopic, 1, true, "test 2");
	Serial.print("Publishing at QoS 1, packetId: ");
	Serial.println(packetIdPub1);
	uint16_t packetIdPub2 = mqttClient.publish(PubTopic, 2, true, "test 3");
	Serial.print("Publishing at QoS 2, packetId: ");
	Serial.println(packetIdPub2);
	printSeparationLine();
	}

Your loop() is really causing the problem by blindly publishing.

Try the unmodified original example FullyFeaturedSSL_ESP32.

---

This is the terminal, showing when losing WiFi, reconnect, then republish normally

Terminal Output

Starting FullyFeatureSSL_ESP32 on ESP32_DEV
AsyncMQTT_Generic v1.8.0 for ESP32 core v2.0.0+
Connecting to Wi-Fi...
WiFi ready
WiFi STA starting
WiFi STA connected
WiFi connected
IP address: 192.168.2.73
Connecting to MQTT...
Connected to MQTT broker: broker.emqx.io, port: 8883
PubTopic: async-mqtt/ESP32_SSL_Pub
************************************************
Session present: 0
Subscribing at QoS 2, packetId: 1
Publishing at QoS 0
Publishing at QoS 1, packetId: 2
Publishing at QoS 2, packetId: 3
************************************************
Subscribe acknowledged.
  packetId: 1
  qos: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 1
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 0
  dup: 0
  retain: 0
  len: 10
  index: 0
  total: 10
Publish acknowledged
  packetId: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 1
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish acknowledged
  packetId: 3
Connecting to Wi-Fi...
WiFi lost connection               <========== Lost WiFi connection and reconnect
Disconnected from MQTT.
WiFi STA connected
WiFi connected
IP address: 192.168.2.73
Connecting to MQTT...
Connected to MQTT broker: broker.emqx.io, port: 8883
PubTopic: async-mqtt/ESP32_SSL_Pub
************************************************
Session present: 0
Subscribing at QoS 2, packetId: 4
Publishing at QoS 0
Publishing at QoS 1, packetId: 5
Publishing at QoS 2, packetId: 6
************************************************
Subscribe acknowledged.
  packetId: 4
  qos: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 1
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 0
  dup: 0
  retain: 0
  len: 10
  index: 0
  total: 10
Publish acknowledged
  packetId: 5
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 1
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish acknowledged
  packetId: 6
Connecting to Wi-Fi...
WiFi lost connection              <========== Lost WiFi connection and reconnect
Disconnected from MQTT.
WiFi STA connected
WiFi connected
IP address: 192.168.2.73
Connecting to MQTT...
Connected to MQTT broker: broker.emqx.io, port: 8883
PubTopic: async-mqtt/ESP32_SSL_Pub
************************************************
Session present: 0
Subscribing at QoS 2, packetId: 7
Publishing at QoS 0
Publishing at QoS 1, packetId: 8
Publishing at QoS 2, packetId: 9
************************************************
Subscribe acknowledged.
  packetId: 7
  qos: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 1
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 0
  dup: 0
  retain: 0
  len: 10
  index: 0
  total: 10
Publish acknowledged
  packetId: 8
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 1
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish acknowledged
  packetId: 9
Connecting to Wi-Fi...
WiFi lost connection
Disconnected from MQTT.
WiFi STA connected
WiFi connected
IP address: 192.168.2.73
Connecting to MQTT...
Connected to MQTT broker: broker.emqx.io, port: 8883
PubTopic: async-mqtt/ESP32_SSL_Pub
************************************************
Session present: 0
Subscribing at QoS 2, packetId: 10
Publishing at QoS 0
Publishing at QoS 1, packetId: 11
Publishing at QoS 2, packetId: 12
************************************************
Subscribe acknowledged.
  packetId: 10
  qos: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 1
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 0
  dup: 0
  retain: 0
  len: 10
  index: 0
  total: 10
Publish acknowledged
  packetId: 11
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 1
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish acknowledged
  packetId: 12
Connecting to Wi-Fi...
WiFi lost connection
Disconnected from MQTT.
WiFi STA connected
WiFi connected
IP address: 192.168.2.73
Connecting to MQTT...
Connecting to Wi-Fi...
WiFi lost connection
Disconnected from MQTT.
Connecting to Wi-Fi...
WiFi lost connection              <========== Power-off/on Router, lost WiFi connection and reconnect
...
Connecting to Wi-Fi...
WiFi lost connection
WiFi lost connection
WiFi lost connection
WiFi lost connection
WiFi STA connected
WiFi connected              <========== Power-off/on Router, lost WiFi connection and reconnect
IP address: 192.168.2.73
Connecting to MQTT...
Connected to MQTT broker: broker.emqx.io, port: 8883
PubTopic: async-mqtt/ESP32_SSL_Pub
************************************************
Session present: 0
Subscribing at QoS 2, packetId: 13
Publishing at QoS 0
Publishing at QoS 1, packetId: 14
Publishing at QoS 2, packetId: 15
************************************************
Subscribe acknowledged.
  packetId: 13
  qos: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 1
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 0
  dup: 0
  retain: 0
  len: 10
  index: 0
  total: 10
Publish acknowledged
  packetId: 14
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 1
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish acknowledged
  packetId: 15
Connecting to Wi-Fi...
WiFi lost connection              <========== Lost WiFi connection and reconnect
Disconnected from MQTT.
WiFi STA connected
WiFi connected
IP address: 192.168.2.73
Connecting to MQTT...
Connected to MQTT broker: broker.emqx.io, port: 8883
PubTopic: async-mqtt/ESP32_SSL_Pub
************************************************
Session present: 0
Subscribing at QoS 2, packetId: 16
Publishing at QoS 0
Publishing at QoS 1, packetId: 17
Publishing at QoS 2, packetId: 18
************************************************
Subscribe acknowledged.
  packetId: 16
  qos: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 1
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 0
  dup: 0
  retain: 0
  len: 10
  index: 0
  total: 10
Publish acknowledged
  packetId: 17
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 1
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish acknowledged
  packetId: 18
Connecting to Wi-Fi...
WiFi lost connection              <========== Lost WiFi connection and reconnect
Disconnected from MQTT.
WiFi STA connected
WiFi connected
IP address: 192.168.2.73
Connecting to MQTT...
Connected to MQTT broker: broker.emqx.io, port: 8883
PubTopic: async-mqtt/ESP32_SSL_Pub
************************************************
Session present: 0
Subscribing at QoS 2, packetId: 19
Publishing at QoS 0
Publishing at QoS 1, packetId: 20
Publishing at QoS 2, packetId: 21
************************************************
Subscribe acknowledged.
  packetId: 19
  qos: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 1
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 0
  dup: 0
  retain: 0
  len: 10
  index: 0
  total: 10
Publish acknowledged
  packetId: 20
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 1
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish acknowledged
  packetId: 21
Connecting to Wi-Fi...
WiFi lost connection              <========== Lost WiFi connection and reconnect
Disconnected from MQTT.
WiFi STA connected
WiFi connected
IP address: 192.168.2.73
Connecting to MQTT...
Connected to MQTT broker: broker.emqx.io, port: 8883
PubTopic: async-mqtt/ESP32_SSL_Pub
************************************************
Session present: 0
Subscribing at QoS 2, packetId: 22
Publishing at QoS 0
Publishing at QoS 1, packetId: 23
Publishing at QoS 2, packetId: 24
************************************************
Subscribe acknowledged.
  packetId: 22
  qos: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 1
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 0
  dup: 0
  retain: 0
  len: 10
  index: 0
  total: 10
Publish acknowledged
  packetId: 23
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 1
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish acknowledged
  packetId: 24
Connecting to Wi-Fi...
WiFi lost connection              <========== Lost WiFi connection and reconnect
Disconnected from MQTT.
WiFi STA connected
WiFi connected
IP address: 192.168.2.73
Connecting to MQTT...
Connected to MQTT broker: broker.emqx.io, port: 8883
PubTopic: async-mqtt/ESP32_SSL_Pub
************************************************
Session present: 0
Subscribing at QoS 2, packetId: 25
Publishing at QoS 0
Publishing at QoS 1, packetId: 26
Publishing at QoS 2, packetId: 27
************************************************
Subscribe acknowledged.
  packetId: 25
  qos: 2
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 1
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 0
  dup: 0
  retain: 0
  len: 10
  index: 0
  total: 10
Publish acknowledged
  packetId: 26
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 1
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish received.
  topic: async-mqtt/ESP32_SSL_Pub
  qos: 2
  dup: 0
  retain: 0
  len: 6
  index: 0
  total: 6
Publish acknowledged
  packetId: 27