Why does Wake On Lan sometimes not work?

Question

network hardware

There is a regular PC based on the Intel Z170 chipset and there is a synology rt2600ac router in the router, it is possible to make WOL from the web interface of the router itself, in most cases everything works, but sometimes the PC does not wake up.
What can be wrong?

Answer 1

for example, how the PC was turned off. in my practice, if power was lost on the power supply (the cable was pulled out, electricity was lost), then the PC could not be woken up via WOL.