KC868-A2 SIM7600 with Tuya GPRS not work

[WestfieldGhost]

Hello everyone,

thank you very much for providing the new beta firmware V2.2.18.
I have tested it together with my KC868-A2 and a SIM7600E-L1C module.

Unfortunately, even with this new firmware, both MQTT and Tuya still do not connect over LTE/GPRS, although they work correctly when the board is on LAN or Wi-Fi.

To confirm that the issue is not related to the SIM7600 hardware or the mobile network, I performed several additional tests:
• The SIM7600E-L1C registers in LTE (Band 1) without problems.
• APN and PDP context are working correctly when the module is tested directly via AT commands on a PC.
• Internet access through LTE works reliably (HTTP 200 responses).
• Baud rate, LTE mode (CNMP=38), and factory settings were all verified.

So LTE connectivity itself is fine, but the KC868 firmware still does not seem to use LTE data for Tuya or MQTT.

Before I continue testing:
Has anyone else already tried this new firmware V2.2.18 with LTE-only operation?
Did you have any success with Tuya or MQTT over LTE, or do you have any additional findings?

Any feedback from other users would be very helpful.

Thank you.