Success !!!!

root@DietPi:~# ip link del wg0
Cannot find device "wg0"
root@DietPi:~# sed -i '/^[[:blank:]]*sleep 1/d' /usr/bin/wg-quick
root@DietPi:~# sed -i '/^ListenPort[[:blank:]]/a\Table = off' /etc/wireguard/wg0.conf
root@DietPi:~# systemctl restart wg-quick@wg0
root@DietPi:~# systemctl status wg-quick@wg0.service
● wg-quick@wg0.service - WireGuard via wg-quick(8) for wg0
Loaded: loaded (/lib/systemd/system/wg-quick@.service; enabled; vendor preset: enabled)
Active: active (exited) since Thu 2019-02-07 12:45:12 CET; 10s ago
Docs: man:wg-quick(8)
man:wg(8)
https://www.wireguard.com/
https://www.wireguard.com/quickstart/
https://git.zx2c4.com/WireGuard/about/src/tools/man/wg-quick.8
https://git.zx2c4.com/WireGuard/about/src/tools/man/wg.8
Process: 3837 ExecStart=/usr/bin/wg-quick up wg0 (code=exited, status=0/SUCCESS)
Main PID: 3837 (code=exited, status=0/SUCCESS)

Feb 07 12:45:12 DietPi systemd[1]: Starting WireGuard via wg-quick(8) for wg0...
Feb 07 12:45:12 DietPi wg-quick[3837]: [#] ip link add wg0 type wireguard
Feb 07 12:45:12 DietPi wg-quick[3837]: [#] wg setconf wg0 /dev/fd/63
Feb 07 12:45:12 DietPi wg-quick[3837]: [#] ip address add 10.8.0.1/24 dev wg0
Feb 07 12:45:12 DietPi wg-quick[3837]: [#] ip link set mtu 1420 up dev wg0
Feb 07 12:45:12 DietPi wg-quick[3837]: [#] iptables -A FORWARD -i wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o $(sed -n 3p /DietPi/dietpi/.network) -j MASQUERADE
Feb 07 12:45:12 DietPi systemd[1]: Started WireGuard via wg-quick(8) for wg0.