TRB255 LEDs

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Main Page > TRB Gateways > TRB255 > TRB255 Manual > TRB255 LEDs

This wiki page contains information about TRB255 gateway LEDs and their actions.

Power LED

The power LED is located on the bottom left corner of the front panel, near the power connector:

Network trb2x5 manual trb2x5 pwr led v1.png

It can perform two different actions:

Action Description
LED turned ON Gateway is powered up
LED turned OFF Gateway is not power up

Ethernet port LEDs

The Ethernet port LEDs are located on the gateway front panel, in both upper corners on Ethernet port:

Network trb2x5 manual trb2x5 eth led v1.png

Since TRB255 gateway supports Fast ethernet speeds, green LED is not used and only orange LED represents information about ethernet connection activity:

Action Description
LED turned ON Operating as a 10/100 Mbps connection
LED turned OFF No link established
LED blinking Connection established and there is activity (data being transferred)
LED blinking fast simultaneously with connection and signal strength LEDs Router is in the bootloader menu state*

* The bootloader menu is a special router state from which certain upgrades can be performed. For more information on the bootloader menu, click here

Connection status LED

The connection status LEDs are located on left side of the back panel:

Network trb255 manual trb255 net led v1.png

Action Description
2G, NB and M1 LEDs are blinking at the same time No SIM or bad PIN
2G, NB and M1 LEDs light up and down in sequence Searching mobile network operator
2G/NB/M1 LED blinking Gateway connected to 2G/NB/M1, no data session established
2G/NB/M1 LED turned ON Gateway connected to 2G/NB/M1 with data session
2G/NB/M1 LED blinking Gateway connected to 2G/NB/M1 and data is being transferred

* NB and M1 is Narrowband IoT (NB-IoT) and LTE Cat M1 communications technologies respectively

Signal strength LEDs

The signal strength LEDs are located on the right side of the back panel:

Network trb255 manual trb255 sig led v1.png

Each lit up LED represents a different value of the gateways current signal strength in RSSi:

No. of lit up LEDs Signal strength value
0 ≤ -111 dBm
1 -110 dBm to -82 dBm
2 -81 dBm to -52 dBm
3 ≥ -51 dBm


The signal strength LEDs can also be used as a time indicator for holding the reset button. When you press and hold the reset button, you have to hold it pressed for 5 seconds (by default) to initiate a factory reset. Depending on a number of signal strength LEDs, time needed to reset router are divided in equal periods, when it passed a new signal strength LED lights up.

In case with TRB255, when all 3 signal strength LEDs are lit up, they represent that 5 seconds have passed since you pressed down on the reset button and you can release it now.

After releasing the button, all 3 LEDs will start blinking every 1 second. This signifies that the router has begun the factory reset.