SIM7670G problems, failures, US. Updates. Now I'm loosing sleep

[Ashton]

Unlike the SIM800L I have experience with, the SIM7670G module core board I'm testing stops responding to commands via UART and to incoming SMS messages after operating perfectly for a few hours, and definitely overnight. The odd thing is, when the SIM7670G core board is connected by USB to a PC(and monitored in Putty or without Putty running) during multi-day tests, does not fail.

I thought when I set the CSCLK=0 to prevent the UART from sleeping, the problem disappeared for a while, but it still fails. Modules like these surely don't require periodic power-cycling to keep them operating do they? I would think the module should be designed to maintain a persistent operating state. I am powering this core board (rated 5-12V input) with a 9V 2A switching power supply. Support from SIMCOM and my core board supplier has been nil.

Some observations(USB serial mon-Putty) during idle standby periods include:
$QCNETDEVCTL: 0
$QCNETDEVCTL: 1
$QCNETDEVCTL: 0
$QCNETDEVCTL: 1
Could not find any reference to these in a web or document search.

Has anyone else had any sort of issues like this with SIMCOM modules?

[b707]

@Ashton

The odd thing is, when the SIM7670G core board is connected by USB to a PC(and monitored in Putty or without Putty running) during multi-day tests, does not fail.

Looks like the modem experienced a power problems.
Please draw a power connection diagram of your Arduino + sim7670 board

[Ashton]

Please draw a power connection diagram of your Arduino + sim7670 board

Now, I'm not using the above board, but a simple breadboard, with no backup battery(BMS), no D1 diode, and a 470uf cap(tested with/without, no difference) on input power. This must not be a power issue as other modules like the SIM7600NA work without fail on the above motherboard and schematic.

The more I work with this board, the stranger this seems.
Regardless of 9VDC 2 or 3 amp power adapter is in use, having the board's USB plugged in a PC(without Putty open) prevents failure. Testing now with a 2.4A USB charging power adapter.