U-Boot set mac address

Hi. I'd want to set a custom MAC address to my cb2. 

I set the static mac address in u-boot environment variable ethaddr. If i print the environment (with "printenv command" i find it right there but when the system starts and i go through ifconfig i can see eth0 has a different MAC.

Any suggestion on how to get MAC from u-boot?

I'm on Armbian 5.20 legacy kernel.

Thank you