MQTT TCP Connect Error

#1

Hi, I want to use my ESP32 with a Telit LE910C1 Cellular Module on Google Iot Core. I have used the pppos and mqtt libraries to achieve this. However as there is an error executing the AT+CGDCONT=1 with Telit from the pppos library, I have done a local build and changed that to AT+CGDCONT=? instead.

When I run my code, the module connects to the internet successfully and starts to send messages to Google IoT core. However, I noticed that the MQTT connection keeps disconnecting and reconnecting every 5 minutes with these error messages:

[May 8 15:50:13.384] mg_ssl_if_mbedtls.c:35 0x3ffd4990 mbedtls_ssl_flush_output() returned -78 (-0x004e)
[May 8 15:50:13.390] mg_ssl_if_mbedtls.c:35 0x3ffd4990 mbedtls_ssl_write_record() returned -78 (-0x004e)
[May 8 15:50:13.394] mg_ssl_if_mbedtls.c:35 0x3ffd4990 mbedtls_ssl_send_alert_message() returned -78 (-0x004e)
[May 8 15:50:13.408] mgos_mqtt.c:164 MQTT Disconnect
[May 8 15:50:13.408] mgos_mqtt.c:493 MQTT connecting after 2053 ms
.
.
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[May 8 15:50:38.545] mg_resolv.c:213 Failed to resolve ‘mqtt.googleapis.com’, server 8.8.8.8
[May 8 15:50:38.552] mgos_mqtt.c:141 MQTT TCP connect error (-1)
[May 8 15:50:38.558] mgos_mqtt.c:164 MQTT Disconnect
[May 8 15:50:38.558] mgos_mqtt.c:493 MQTT connecting after 8672 ms

I am running a similar system using a SIMCOM 7600E module and am not encountering this error. I am able to build on the cloud for this.

My question is: Is there any difference with the cloud build and the local build that could be contributing to this error? Or is there another issue here?

#2

It looks like your module gets disconnected.
Error -0x004e

Failed to resolve... indicates the same thing.