The wiki tells us we need to run ethtool -s <interface> wol g when the interface comes up.

Although Ubuntu 20.04 has ifupdown scripts under /etc/network/if-up.d, Netplan provides different guidance on how to run post-up hook scripts that suggests using networkd-dispatcher.

The manual page for networkd-dispatcher does not explain how to detect which interface is going down but the source code shows several environment variables that get set including IFACE.

So we can create /etc/networkd-dispatcher/routable.d/50-wake-on-lan (and chmod +x it) with a script like this:

#!/bin/sh -eu



case "$IFACE" in

    enp60s0)

        ethtool -s <interface> wol g

        ;;

esac