I have a MKR NB1500 (SARA-R410M-02) sending specific text message responses when text message commands are received, e.g. inbound message 'status', response message 'open', that I had the 'normal' random modem disconnect/offline issues with firmware lower than 5.12.
After getting ahold of the MKR NB1500 upgrader PCB (here) I was able to update the firmware to 5.12. ATI9 reports L0.0.00.00.05.12,A.02.19 and AT+CGMR reports L0.0.00.00.05.12 [Oct 08 2020 15:00:01]
I had hoped that the 5.12 firmware would resolve the connection issues, but it seems they are worse. Now I am experiencing the 'single text message per modem restart' issue that has been reported on earlier firmware versions, and the modem appears to go offline as soon as it is disconnected from the computer, even though a fully-charged battery is connected.
I've tried the SAMD board libraries at versions 1.8.9, 1.8.11, and 1.8.13, without any improvement.
I'm not sure where to go from here, except maybe downgrading the firmware to 5.08, but that seems less than ideal because there are still significant issues with that version.
Open to ideas on how to proceed to get this board to be as responsive as I think it should be.