I am using a large number of RM520N-GL modems.
However, in rare cases (approximately 1 out of 20 units), the modem fails to detect a USIM in Slot 1, while Slot 2 works normally.
Changing the slot using the AT+QUIMSLOT command does not resolve the issue.
In the past, our local distributor was able to fix similar cases through a firmware update, but for this particular modem, updating to the latest firmware does not solve the problem.
Could you please advise on how this issue can be resolved?
The number of RM520N-GL units that require an immediate fix is one modem at the moment.
For devices that can operate with USIM Slot 2, we were able to complete deployment by configuring the modem with “AT+QUIMSLOT=2”
However, for devices that require USIM Slot 1, we currently have no workaround, as Slot 1 is not detected on the affected modem.
Since no USIM-related issues had occurred for quite some time, we began purchasing RM520N-GL modules directly from an online dealer in China, instead of through the local distributor.
Because of this, we are unable to receive local distributor support for the affected unit.
We would appreciate any guidance or recommended procedures to resolve this issue, especially for restoring proper operation of USIM Slot 1.