Enable Wake-On-Lan

Follow this guide, if for some reasons Wake-On-Lan is not working, even if you enabled it in the BIOS.

Get all ethernet interfaces:

ip a 

Check if it supports WoL using ethtool.

sudo apt install ethtool

# enp1s0 could be different on your machine
sudo ethtool enp1s0

The output will look something like this:

Settings for enp1s0:
    Supported ports: [ TP    MII ]
    Supported link modes:   10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
                            1000baseT/Full
    Supported pause frame use: Symmetric Receive-only
    Supports auto-negotiation: Yes
    Supported FEC modes: Not reported
    Advertised link modes:  10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
                            1000baseT/Full
    Advertised pause frame use: Symmetric Receive-only
    Advertised auto-negotiation: Yes
    Advertised FEC modes: Not reported
    Link partner advertised link modes:  10baseT/Half 10baseT/Full
                                         100baseT/Half 100baseT/Full
                                         1000baseT/Full
    Link partner advertised pause frame use: No
    Link partner advertised auto-negotiation: Yes
    Link partner advertised FEC modes: Not reported
    Speed: 1000Mb/s
    Duplex: Full
    Auto-negotiation: on
    master-slave cfg: preferred slave
    master-slave status: slave
    Port: Twisted Pair
    PHYAD: 0
    Transceiver: external
    MDI-X: Unknown
    Supports Wake-on: pumbg
    Wake-on: g
    Link detected: yes

Note the line Wake-on: g.
g means enabled, d is disabled.

If you want to enable it permanently you can do so in a netplan configuration file:

/etc/netplan/99_tooloop.yaml

network:
  version: 2
  renderer: networkd
  ethernets:
    enp1s0:
      dhcp4: true
      wakeonlan: true
    enp2s0:
      dhcp4: true
      wakeonlan: true