I use an MQTT to communicate with an ESP8266. I'm using cloudmqtt.com and PubSubClient. Sometimes the ESP disconnects from the MQTT and reconnects. I checked the log from cloud and I got this data

2019-02-18 20:11:18: New connection from on port 18127.

2019-02-18 20:11:22: New connection from on port 18127.

2019-02-18 20:11:35: New connection from on port 18127.

2019-02-18 20:11:35: New client connected from as ESP8266Client-80:7D:3A:69:6C:2E (c1, k15, u'userName').

2019-02-18 20:11:53: Client <unknown> has exceeded timeout, disconnecting.

2019-02-18 20:11:53: Socket error on client <unknown>, disconnecting.

2019-02-18 20:11:56: Saving in-memory database to /var/lib/mosquitto/18127/db.

2019-02-18 20:11:58: Client ESP8266Client-80:7D:3A:69:6C:2E has exceeded timeout, disconnecting.

in setup I have this method:

void setupMQTT() {

  while (!client.connected()) {
    Serial.println("Connecting to MQTT...");
    String clientId = "ESP8266Client-";
    clientId += WiFi.macAddress();
    if (client.connect(clientId.c_str(), mqttUser, mqttPassword )) {


    } else {

      Serial.print("failed with state ");

  client.publish("esp/blind/out", "hello world");

and in loop I have


without any delay.

I think that the ESP id in MQTT cloud is unique, because I use the MAC address.

  • which version of arduino/esp8266 are you using - I ask, because I had to put in a delay(10) or so in loop for some ESP chips when using the latest (2.5.0dev) branch Feb 19 '19 at 0:42
  • I use wemos D1 mini with ESP-12F and about month ago I update firmware because I wanted to try micropython Feb 19 '19 at 8:40
  • but your code isn't written in micropython .... it looks like typical arduino (i.e. C/C++) ... which version of the esp8266 arduino core are you using? Actually, nevermind, try adding a delay(10) in your main loop or even a yield() Feb 19 '19 at 9:26
  • no it isn't written in micropython it's written in c++, adding delay(10) do nothing. How can I check a esp8266 arduino core version ? Feb 19 '19 at 20:30
  • you downloaded it and installed it ... what did you download and install ... another possibility is the router you connect to- which make model? (e.g I have a linksys wrt32x - and ESP's have lots of issues staying connected to it)\ Feb 19 '19 at 20:33

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