All DM devices require the correct APN to be set so that they can connect on the network. A list of APNs is stored in device FW, and in the majority of cases, the device will detect the network of the SIM card it is using and select the right APN from this list.
On 2G and 3G devices, if the APN is not on the list, the device can be sent an SMS to set the APN. Even if the APN is not yet set, the SMS can still be received and applied.
On 4G Cat-M1 and Nb-IoT, this is not the case. An SMS cannot be received if the device isn't on the network - so configuring APNs and other connectivity settings is not so simple. To assist with this, Digital Matter has developed a wired tool to enable parameters to be set on the device using a cable and app - and also read some debug information from the device to shed light on why a device may not be connecting.
Download the tool HERE.
The tool requires Windows 7 or above.
The Programming Tool comes loaded with FW for each device, and updates the firmware automatically before setting the Admin Parameters. The bundled firmware may not be the latest firmware, so using the tool will sometimes result in a firmware downgrade.
Setting the firmware and Admin Parameters can be a useful debugging tool. If incorrect settings were previously applied, a device should be able to reconnect after this. If it is doesn't there is likely a hardware fault.
To program the FW:
The screen should flash blue, and the device's serial number, hardware revision, and FW revision should be shown. If the firmware needs to be updated, a progress bar will pop up during the update.
As described in this article, the modem's internal network profiles may need to be updated to add support for DNS on certain NB-IoT networks. Checking the Set Modem Profiles checkbox before inserting the adapter cable will cause the tool to power up the device's modem and update the profiles if required. This adds a few seconds to the programming cycle, during which a dialog box displays the progress.
You can take advantage of this to check the modem function when debugging devices that are suspected faulty. If the modem is not responding, an error message will be displayed during the modem profile check. If the device has a stable power supply, and the modem is not currently attempting to update its firmware, an error message during the profile check is a good indicator of faulty hardware.
If the modem is busy trying to update its firmware, the profile update cannot be run. You can restart the device and leave it on power for 30 minutes to allow the firmware update to complete.