If you have the option in your BIOS , Make the LAN first in the Boot order.
Thanks for your reply !
I have the option and made LAN first in boot order, but it doesn't work. Even if I disable the onboard LAN port...
It looks like mainboard doesn't accept any other LAN boot interface except its own onboard port...
For information, the BIOS has been updated to the latest version available...
Have you tried going into Device Mng. and disabling the onboard LAN there ??