ESP32-S3 + SIM7672G: SSL connection takes too long using SSLClient library (over 1 minute)

[Rushik]

'm working on a project using an ESP32-S3 connected to an LTE modem (SIM7672G). I'm using the SSLClient library to establish an SSL connection for MQTT communication.

However, I'm facing an issue:

The SSL connection takes about 1 minute to establish when using the SIM7672G modem.

Interestingly, when I switch to another modem, the SIMCOM A7672G, using the exact same code and setup, the SSL connection is established almost instantly.

Details: Both modems (SIM7672G and A7672G) are similar in specs.

I'm not using AT commands for SSL or MQTT — the ESP32 handles the SSL stack directly via the SSLClient library.

I did test AT commands for SSL and MQTT as a workaround, and while it works, it’s not suitable for my project as I require MQTT to run through the ESP32 stack, not the modem.

The network signal and SIM card are the same in both cases.

My Questions: Why might the SIM7672G be significantly slower in establishing an SSL connection compared to the A7672G?

Is there something specific in the SIM7672G that could affect TCP/SSL performance?

Is there any known compatibility issue between SIM7672G and the SSLClient library or ESP32-S3?

I’d appreciate any insights or suggestions on debugging or optimizing this setup. If needed, I can also share code snippets.

Thanks!