Hi everyone,
I’m using a TRB501. Recently, if LTE B3 is selected as the primary/anchor band, the modem fails to attach to 5G n78. However, when LTE B7 is the primary band, 5G n78 works perfectly.
I would like to ask two specific questions regarding this setup:
-
Cell Lock AT Command Syntax To force LTE B7 as the primary cell (EARFCN: 3175, PCI: 11), what is the exact and safest AT command for the internal Quectel modem on the TRB501? Is gsmctl -A 'AT+QNWLOCK="common/4g",1,3175,11' the correct syntax?
-
Persistence Across Reboots Is this cell lock persistent after a system reboot or power cycle? If not, what is the best/recommended way in RUTOS to make it persistent (e.g., adding a startup script in /etc/rc.local or another native feature)?
Firmware: TRB501_R_00.07.24.3
Modem: RG520NEBDCR03A02M4G_OCPU_02.200.00.000.bin
Thanks in advance for your support!
Greetings,
To verify the supported cell-lock syntax for your modem model and firmware, run:
gsmctl -A ‘AT+QNWLOCK=?’
The response will most likely include:
+QNWLOCK: “common/4g”,(0-10),(freq),(pci)
If your modem returns this format, the command you proposed is correct for locking to LTE EARFCN 3175, PCI 11:
gsmctl -A ‘AT+QNWLOCK=“common/4g”,1,3175,11’
The lock is not retained after a reboot. To reapply it automatically, go to System → Maintenance → Custom Scripts in the device’s WebUI and add the same command to the startup script, before exit 0.
Save the changes. The startup script will execute the command after each restart. After rebooting, check the serving-cell information to confirm that the lock was successfully reapplied.
Regarding B3, your operator may not have enabled 5G n78 to work with the B3 cell you are connected to, while it is enabled on the B7 cell. Selecting B3 could also connect you to a different tower with different 5G availability.
If you have any issues, please let us know.
Best regards,
T.