I am trying to connect to an a mosquito broker hosted on AWS, on port 8883, but so far I have not been successful. I am using the TinyGSM and PubSubClient libraries.
The GSM module is connected to the internet and works perfectly in a broker without SSL. But when I try to switch to SSL, he can't connect and the MQTT client returns -2. But this error is not very clear, as you can see here in the PubSub documentation.
#define MQTT_CONNECT_FAILED -2
These are the AT commands that it performs to try to connect to the broker
AT+CIPRXGET=4,0
+CIPRXGET: 4,0,0
OK
AT+CIPSTATUS=0
+CIPSTATUS: 0,0,"TCP","3.13.162.221","8883","CLOSED"
OK
* Trying to connect to the MQTT Broker: <broker_url>
AT+CIPCLOSE=0,1
ERROR
AT+CIPSSL=1
OK
AT+CIPSTART=0,"TCP",<broker_url>,8883
OK
Failed to reconnect to the broker.
Status: -2
Some useful parts of the code
void setupGSM() {
SerialMon.println("Setup GSM...");
modem.sendAT("+SSLOPT=1,1");
if (modem.waitResponse() != 1) {
SerialMon.printf("modem +SSLOPT=1,1 failed");
}
while (!modem.gprsConnect(APN, APN_USER, APN_KEY)) {
SerialMon.println("GPRS Connection Failed");
modem.restart();
delay(1000);
}
SerialMon.println("GPRS Connection Success");
}
void reconnectMQTT() {
while (!MQTT.connected()) {
SerialMon.print("* Trying to connect to the MQTT Broker: ");
SerialMon.println(BROKER_MQTT);
initMQTT();
if (MQTT.connect(ID_MQTT, MQTT_USERNAME, MQTT_KEY)) {
SerialMon.println("Successfully connected to the MQTT broker!");
MQTT.subscribe(RECEIVED_CREDITS);
}
else {
SerialMon.println("Failed to reconnect to the broker.");
SerialMon.print("Status: ");
SerialMon.println(MQTT.state());
delay(2000);
}
}
}
The question is, how can I connect to an MQTT broker with SSL using the sim800l module?
Info:
Modem: SIMCOM_SIM800L R14.18
Main processor board: TTGO-T-Call ESP32
TinyGSM Version: 0.10.5
