Ethernet problem

I’ve a problem with Ethernet on HiKey970 board.
Leds on Ethernet connector remain off and I cannot see Ethernet connection on Lubuntu.
I also tried to connect cable before turning on the board but is the same.
I saw that the ethernet controller is mounted on the pci express.
Do I have to activate some switches or some software command?
Does Ethernet also work with other connected PCI devices or are they mutually exclusive (this is not my case)?
My OS version is Lubuntu 16.04 kernel 4.9.78-147538.

Thank you in advance