After creating a systemd service run the following

sudo systemctl daemon-reload

Then these commands as necessary:

• sudo systemctl enable caddy
• sudo systemctl start caddy
• sudo systemctl stop caddy
• sudo systemctl reload caddy (after a config change saves restarting)

The Caddyfile is in /etc/caddy

sudo systemctl start php-fpm.service

The Caddyfile needs this line

php_fastcgi unix//run/php-fpm/www.sock