EC25, LTE, +QMTOPEN: 0,-1 Issue

Hi there,

I am developing MQTTS Logic using EC25-E.
However, when MQTT is open, +QMTOPEN: 0,-1 is obtained and the connect is also impossible.
It seems to be a problem that many people have encountered in the past, but I haven’t been able to find a solution.

So my question is…

  1. How can I update the latest firmware for EC25-E?
  2. The final destination is Google IoT Core (GCP), and I have only the client_key. Many devices communicated only with the client_key, is it okay not to input CA_cert and client_cert?
  3. How have others solved the problem?
  4. Is it a problem between MCU and EC25? Regardless of the server?

1、If you are using a domain name, run AT+QIDNSCFG to configure DNS,And verify that the domain name can be resolved by AT+QIDNSCFG
2、You will also need to test the validity of CA certificates and servers with the MQtt.fx tool

Can this not omit the CA, Client cert?
I use only clent key for other device

I recommend you use MQtt.fx for debugging and validation

How many bytes can the password be when doing AT+QMTCONN?
Because Google GCP uses a password for the JWT certificate, it is very long (about 600 bytes), so ERROR continues to occur. Is this correct?

General CA certificates are loadable

I mean, the password when doing AT+QMTCONN…
Do you have the GCP(google iot core) experience?

Sorry, I have no experience with GCP, I suggest you try AWS