MQTT fails to connect with static ip (wifi.config())

Projects Programming
1

I have searched a lot regarding this problem but unable to find a solution. I have connected my esp8266 with mqtt broker successfully and is working perfectly. Now I want to make IP static so I've used wifi.config(ip, gateway, subnet) to do the same but now the connection with my mqtt broker fails with state -2. Both the codes i.e. wifi.config() and mqtt connection code works perfect independently but not together. I am using node mcu esp8266 board. Code is given below:-

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

const char* ssid = "ai***l";
const char* password =  "j***se";

const char* mqttServer = "i***l.c****tt.com";
const int mqttPort = 1**8;
const char* mqttUser = "w*****e";
const char* mqttPassword = "H*******7";

IPAddress staticIP(192, 168, 1, 200);
IPAddress gateway(192, 168, 1, 1);  
IPAddress subnet(255, 255, 255, 0);  

int led = D1;

WiFiClient espClient;
PubSubClient client(espClient);

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

  WiFi.config(staticIP, subnet, gateway); //problem with this line
  WiFi.begin(ssid, password);
 
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.println("Connecting to WiFi..");
  }
  Serial.println("Connected to the WiFi network");

  delay(500);
 
  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);

  while (!client.connected()) {
    Serial.println("Connecting to MQTT...");
 
    if (client.connect("ESP8266Client", mqttUser, mqttPassword )) {
 
      Serial.println("connected");  
 
    } else {
 
      Serial.print("failed with state ");
      Serial.println(client.state());
      delay(2000);
 
    }
  }
  client.subscribe("esp/node");

  delay(500);
  pinMode(led, OUTPUT);
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.println((char) payload[0]);
}

void loop() {
  client.loop();
}

Please help me to find a solution to this problem.

2

I'm having the same issue. Were you able to find a resolution?

3

Have you tried using the actual IP adreess of the mqtt server instead of the dns name?
I suspect a dns name resolution issue when the local ip address is staticly defined.

4

Sorry but i hadn't found any solution yet. Instead of using static ip you can use dynamic ip only. You can fetch dynamic ip over mqtt connection or fetch it from your router i.e. get ip using hostname or mac address from DHCP connected devices.

5

Did you see my post #2 ?

6

I will definitely try it. But since ip changes, it might not be a best way.

7

I will definitely try it. But since ip changes, it might not be a best way.

The mqtt server IP address doesn't change.

const char* mqttServer = "i***l.c****tt.com";

replace the line above with actual IP address of the MQTT server

 IPAddress MQTTServer (192, 168, 10, 210);

The above is the local IP of my own MQTT broker. I have installed mosquito MQTT broker.
If you are using a public server, just replace the above IP with that of the server.

Alternatively you have to also define the DNS server address when you use static IP settings:

WiFi.config(ip, dns, gateway, subnet);

Also check out the syntax of wifi.config( ). I am under the impression that the second parameter in the above function is the DNS and not the gateway as in your sketch.
This could also be the reason why the ESP cannot find the broker.

Please do let us know if it works out...

1 Like
8

I have got similar problem and this proposed solution works for me.
In some example there was wrong syntax: WiFi.config(ip, gateway, subnet);

Correct one is: WiFi.config(ip, dns, gateway, subnet);

Thank you.