Hello,
I am using MQTT+TLS on nRF9160DK. In the development stage, I followed this link https://devzone.nordicsemi.com/guides/cellular-iot-guides/b/software-and-protocols/posts/enabling-and-testing-tls-in-mqtt_5f00_simple to use MQTT+TLS. Everything worked properly without any errors.
Now we are in the pre production. We have created 50 custom boards with nRF9160 on it. I created the tls certificates and programmed in the similar manner. All the custom boards could connect to the mqtt server and there was the communication between nRF9160 and the mqtt server.
After 3-4 months of testing, on few cards there is mqtt connect -45 error. Before few days these cards were completely functional.
I am using sec_tag 16842753. Can I use this sec_tag? What might be the cause of this error?
I re-programmed few non-functional cards by putting the application file + certificates in this way:
cred.py --CA_cert root.crt --client_cert BT36-chain.crt --client_private_key BT36.key --sec_tag 16842753 --program_app nRF9160.hex
These cards are working again.
So the question is why the cards doesn't connect to the mqtt server after few days even after the application hex file and the certificates are same?