Ubuntu cannot be resumed by WOL after first BOOT (from 4.15->4.19rc)

Question

Dears,

I've annoying bug with my ubuntu ( tested kernel 4.15.x -> 4.19rc)

Test Case1 :

First coldBoot

systemctl suspend

Try to resume by WOL ( not working )

resume by keyboard

systemctl suspend

resume by WOL is working

Test Case2:

First coldboot

Systemctl poweroff

Try to resume by WOL ( not working ) -> need to restart by power button

Test Case3:

First coldboot

sudo /usr/sbin/rtcwake -v -m mem -s 5

Systemctl poweroff

Resume by WOL works

BUT! if If Systemctl poweroff -> I can't resume by WOL !!!

My Bios is properly configured to access WOL ( and it works the second times , Wakeup properly set in linux :-(

I don't feel it's a driver issue, but more a linux parameter that change from first -> second suspend... Could you provide me some guidance ?

Thanks a lot in advance JP