RB4011iGS red light problem?

Hello!
The RB4011iGS + 5HacQ2HnD-IN started to glow at the bottom of the red light. What could it be? I can’t find any info on such a miracle. Everything is working, the board is not overheating, the processor is not overloaded. What can it have to do with it?
Thank you!

It is leds on the R11e wireless modem, they lit when 2.4Ghz link is established.

It is normal? Is it for all these models?

solved the problem. Someone might find the information useful.
I had 6.43 firmware on this router. When changing the option in the system-Led section nothing changed. I installed the latest version 6.46.3 and only then did everything work correctly in the system-led section.