Wake on LAN (WOL) for Ubuntu 20
dito Proxmox but with orhter path for ethtool:

nano /etc/systemd/system/wol.service

[Unit]
Description=Wake-on-LAN for <interface id>
Requires=network.target
After=network.target
[Service]
ExecStart=/sbin/ethtool -s <interface id> wol g
ExecStop=/sbin/ethtool -s <interface id> wol g
[Install]
WantedBy=multi-user.target

systemctl start wol.service
systemctl enable wol.service
systemctl is-enabled wol.service
systemctl daemon-reload

Wake on LAN (WOL) for Ubuntu 18 (Bionic)

On a server without GUI = with “Netplan” and without “Network-manager”
https://askubuntu.com/questions/1053302/wake-on-lan-not-working-if-i-turn-of-with-ubuntu

Send a Magic Packet at startup for Ubuntu 20
Useful to wakeup a server when the client starts.

$ sudo nano /etc/systemd/system/wol-omv.service
[Unit]
After=network-online.target
Wants=network-online.target
[Service]
ExecStart=/usr/local/bin/wol-omv.sh
[Install]
WantedBy=default.target

sudo nano /usr/local/bin/wol-omv.sh
#!/bin/bash
/usr/sbin/etherwake -i enp34s0 69:70:BC:AD:4B:A2 ///// use your correct interface name and the correct mac address!!

sudo chmod 744 /usr/local/bin/wol-omv.sh
sudo chmod 664 /etc/systemd/system/wol-omv.service

sudo systemctl start wol-omv.service
sudo systemctl enable wol-omv.service
sudo systemctl daemon-reload

Script pour contrôler que la machine qui a recu le paquet magique s'est bien lancée - peut être ajouté au script de WOL:

# enter le suffixe de l'adresses de la machine à surveiller - sur réseau: 192.168.20.0
ip=(69)
for i in `seq 1 10`; do
echo "test ping sur IP 192.168.20."$ip":";
if $(ping -c 1 192.168.20.$ip &> /dev/null) ; then
echo "machine 192.168.20."$ip" en ligne"
beep -f 1000 -n -f 2000 -n -f 1500
exit
else
echo "machine 192.168.20."$ip" pas présente"
sleep 10s;
fi
done
echo "machine 192.168.20."$ip" pas présente"
beep -f 300.7 -r 2 -d 100 -l 400