MC7430 disconnected after a period of time and unable to recover until power cycled

Hi all,

I am trialling an SBC computer (Advantech ITA5831) with a 4G module MC7430 and in the future will be MC7421 with Telstra APN SIM) on our locomotive (moving) and we are experiencing a problem.

After a period of time, 4G modem suddenly lost connection to the carrier and unable to recover until power cycle.

can you please help me to have a look at this?

Thank you.

What is the return of "at!gstatus? "

Hi jyijyi, thank you for your reply. I currently lost contact with the unit (it is on the train in the network) so I am unable to do anything now. Once it reached the terminal, I can asked someone to reset the computer so I can access to it remotely however, by doing that "at!gstatus? " won’t return anything useful and the issue is cleared after power cycled.
Please note that in lab environment (we had the same unit running in the lab 3 to 4 days before installing it on the train and another unit had been running for a few months as a part of the lab testing), the signal was quite stable and rssi was always at around -65dBm but when it was on locomotive running in the network, we logged rssi and found that it fluctuated between -40dBm to around -105dBm. When the issue happened, the rssi seemed to be OK.
I just found that the firmware of the modem is possibly the generic firmware not Telstra one (the service provider we are using). I am not sure if this can cause this strange issue to happen (when signal is unstable and keep changing between 3G and 4G (regional areas)).
Thank you.