正在尝试 MQTT 连接...失败，rc=-4 5 秒后重试

Question

我使用 aREST 访问我的 NODEMCU，但它在串行监视器上显示“正在尝试 MQTT 连接...失败，rc=-4 5 秒后重试”

我的代码：

// Control ESP8266 anywhere

// Import required libraries
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <WiFiClientSecure.h>
#include <aREST.h>

// Clients
WiFiClient espClient;
PubSubClient client(espClient);

// Create aREST instance
aREST rest = aREST(client);

// Unique ID to identify the device for cloud.arest.io
char* device_id = "aliziveh79";

// WiFi parameters
const char* ssid = "Samsung J7";
const char* password = "Movahed12341234";

// Functions
void callback(char* topic, byte* payload, unsigned int length);

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

  // Set callback
  client.setCallback(callback);

  // Give name and ID to device
  rest.set_id(device_id);
  rest.set_name("relay_anywhere");

  // Connect to WiFi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Set output topic
  char* out_topic = rest.get_topic();

}

void loop() {

  // Connect to the cloud
  rest.loop(client);

}

// Handles message arrived on subscribed topic(s)
void callback(char* topic, byte* payload, unsigned int length) {

  rest.handle_callback(client, topic, payload, length);

}

我使用 aREST 访问我的 NODEMCU，但它在串行监视器上显示 Attempting MQTT connection...failed, rc=-4 try again in 5 seconds"

Answer 1

Return code -4 是尝试连接到代理的超时

// Possible values for client.state()
#define MQTT_CONNECTION_TIMEOUT     -4
#define MQTT_CONNECTION_LOST        -3
#define MQTT_CONNECT_FAILED         -2
#define MQTT_DISCONNECTED           -1
#define MQTT_CONNECTED               0
#define MQTT_CONNECT_BAD_PROTOCOL    1
#define MQTT_CONNECT_BAD_CLIENT_ID   2
#define MQTT_CONNECT_UNAVAILABLE     3
#define MQTT_CONNECT_BAD_CREDENTIALS 4
#define MQTT_CONNECT_UNAUTHORIZED    5

这很可能意味着您的代理地址错误（但我看不到您在提供的代码中指定的位置）

Answer 2

当你连接客户端时，你必须更改设备的名称：

 if (client.connect("CHANGE_THIS_IT_HAS_TO_BE_DIFFERENT_FOR_EACH_DEVICE"))

我使用 MAC 地址来动态更改它