However, an APC UPS can help after a power outage.
Ensure the "Turn off the UPS" or "Kill Power" option is unchecked or configured with a significant delay. If the UPS cuts outlet power, the network card dies, and WoL becomes impossible.
To solve this, you need a UPS that can "remind" the computer to turn on once power is restored. This is where and delayed power sequencing come into play.
Using the APC Network Management Card web interface (or PowerChute Serial/USB):
# Send standard WoL magic packet wakeonlan $SERVER_MAC
This is the most common point of failure. You are not using WoL for the initial boot; you are using AC power restoration.