I have the puzzling problem with a new NAS I am setting up.
First of all, I checked
cat /proc/acpi/wakeup | grep enabled
and disabled everything from waking up the system except for the two NICs it has. Then, if I set using ethtool the wol flag to d which disables everything, the NAS can go to sleep and stay asleep indefinitely.
However, if I set the wol flag to anything else, the NAS will sleep but wake up almost instantly, like I pressed the power button right after it has slept.
I have tried other wol flags like u and b, both did the same to cause the NAS to wake up instantly. What maybe set to fix this?