EC200U-EU-C4-P01 (qpyver=V0004): ussl.wrap_socket TLS handshake hangs to timeout on cloud MQTT broker

QuecPython
1

Module: EC200U-EU-C4-P01
Firmware: EC200UEUAAR03A04M08_OCPU_QPY

uos.uname() reports:
sysname=EC200U-EUAA, release=1.13.0, version=v1.12 on Mon_Jan_13_2025,
qpyver=V0004

Issue: ussl.wrap_socket() hangs until socket timeout during the TLS
handshake to a standard cloud MQTT broker (HiveMQ Cloud, port 8883,
username/password auth, CA-trust only — no client certificate). The
same failure occurs independent of umqtt: I reproduced it directly with
raw usocket + ussl, isolating each layer.

Confirmed working before the handshake:

  • LTE registration and PDP context activation
  • DNS resolution of the broker hostname
  • Raw TCP connect to the broker on port 8883 (succeeds in ~200ms)

Confirmed failing:

  • ussl.wrap_socket(sock, server_hostname=host) on that same, already-
    connected socket hangs for the full timeout, then raises
    OSError: (110,) [ETIMEDOUT]
  • Same result with server_hostname omitted (SNI not the cause)
  • Same result going through umqtt.MQTTClient directly (ssl=True,
    ssl_params={}) — not a parameter or config issue
  • Same result over WSS (uwebsocket.Client.connect to the broker’s
    8884 WebSocket-TLS endpoint) — same underlying TLS layer, same hang

This closely matches two other threads on this forum reporting the same
handshake-hangs/fails pattern on EC200U-family modules connecting to
cloud MQTT/IoT brokers over TLS:

In the second thread, Quectel support provided an updated firmware
build (A13M08 → A17M08) to the reporter. I’d like to request the
equivalent current firmware build for the EC200U-EU-C4-P01 / qpyver
V0004, to test whether it resolves this handshake issue.

Could you confirm:

  1. Is there a known TLS handshake issue in this firmware’s ussl/mbedTLS
    implementation affecting connections to modern cloud brokers?
  2. Is a newer QuecPython firmware build available for this module
    variant, and if so, could you provide it?

Happy to share the full isolation test scripts and logs if useful.

2

Could you please provide your server address and certificates? let me try on my side.