cat<<EOF>/etc/systemd/system/certbot-renew.service
[Unit]
Description=Renew Let's Encrypt certificates service

[Service]
Type=oneshot
ExecStart=/usr/bin/certbot renew --post-hook "/usr/bin/systemctl reload nginx" --quiet
#ExecStart=/usr/bin/certbot renew --standalone --pre-hook "/usr/bin/systemctl stop nginx" --post-hook "/usr/bin/systemctl start nginx" --quiet

EOF

cat<<EOF>/etc/systemd/system/certbot-renew.timer
[Unit]
Description=Renew Let's Encrypt certificates timer

[Timer]
#Every year, month and day at 18 and 4 
OnCalendar=*-*-* 04,18:36:28
Persistent=true

[Install]
WantedBy=multi-user.target

EOF

systemctl enable certbot-renew.timer
systemctl start certbot-renew.timer

# To check:
# systemctl list-timers