TRB255 BG96 Modem: Tower Selection Issues

[xmtbiker]

Hello,

We are experiencing issues with several TRB255/256 units in the field where the devices do not always switch to the strongest available LTE-M cell, sometimes remaining on a weaker tower much longer than expected. You can see the tower stays on a much weaker signal far too long despite the other, better signal being available. These are stationary devices.

Device & Firmware Details:

TRB255 Firmware Version: TRB2_R_00.07.14.4
Firmware Build Date: 2025-09-11 20:43:44
Kernel Version: 5.4.290
Internal Modem: Quectel BG96
Modem Firmware Version: BG96MAR02A11M1G_01.016.01.016

Current Observations:

# Check RAT scan mode
gsmctl -A 'AT+QCFG="nwscanmode"'
+QCFG: "nwscanmode",0  # automatic scan (LTE-M + NB-IoT + GSM)

# Attempt to check IRAT timers
gsmctl -A 'AT+QCFG="irat"'
ERROR  # Not supported on BG96

• WebUI shows no modem firmware updates available.

• The devices are generally stable, but reselection behavior is suboptimal to say the least in some areas.

Questions / Assistance Requested:

1. Is there a newer BG96 modem firmware supported for TRB255 that improves LTE-M / NB-IoT / GSM reselection or attach behavior?

2. If available, can you provide the version number, changelog, and instructions for safe update?

3. Are there recommended settings (e.g., nwscanmode, band locks) or best practices to improve LTE-M tower selection on BG96?

We appreciate any guidance or advice — our goal is to ensure stable LTE-M connections for our field devices.

[xmtbiker]

@Marija @Matas Have you guys seen this before? Happy to share logs/files as needed.

[Justinas]

Greetings,

For troubleshooting purposes, we will require more sensitive information from your end, such as the troubleshoot file, which may contain passwords, public IP addresses, serial numbers, and such. To avoid leaking this information, we have sent you a form to fill out, which you will receive in your e-mail inbox that you have registered your account with in the forums. In the Ticket ID field of the form, please enter the ID of this thread, which is 16494

Best Regards,
Justinas