Hello Quectel Team,
I am using FCM360WA with firmware FCM360WAAR01A04.
I am trying to connect to an MQTT broker using TLS 1.2 with mutual TLS (mTLS) on port 8883.
My SSL configuration is:
AT+QMTCFG=“ssl”,0,1,2
AT+QSSLCFG=“sslversion”,2,3
AT+QSSLCFG=“ciphersuite”,2,0xC024
AT+QSSLCFG=“sni”,2,0
AT+QSSLCFG=“seclevel”,2,2
AT+QSSLCFG=“ignorelocaltime”,2,1
AT+QSSLCFG=“cacert”,2,“UFS:ca_bundle_v3.pem”
AT+QSSLCFG=“clientcert”,2,“UFS:client_v4.pem”
AT+QSSLCFG=“clientkey”,2,“UFS:client_key_v4.pem”
All configuration commands return OK.
The certificate files are stored successfully in UFS and verified byte-for-byte.
However, MQTT open fails with:
AT+QMTOPEN=0,“”,8883
+QMTOPEN: 0,-1
I also tested the TLS connection directly:
AT+QSSLOPEN=2,4,“”,8883,0
+QSSLOPEN: 4,550
So the failure is happening during the TLS handshake before MQTT authentication.
The same CA certificate, client certificate and client private key work successfully from a PC using OpenSSL with TLS 1.2 and cipher:
ECDHE-ECDSA-AES256-SHA384
This corresponds to:
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384
Cipher ID: 0xC024
Please confirm:
- What exactly does QSSLOPEN error 550 mean on FCM360WA?
- Does FCM360WAAR01A04 fully support an ECDSA server certificate with cipher 0xC024?
- Is there any known TLS/mTLS issue in A04?
- Is a newer standard AT firmware available for FCM360WA?
- If yes, please provide the recommended firmware version, flashing tool and release notes.
Thank you.