service status: systemctl status caddy logs: journalctl --no-pager -u caddy are your site's files readable by the caddy user and group? ls -la /var/www/html is the caddy home directory writeable? ls -la /var/lib/caddy ensure your domain's a and/or aaaa records point to your machine's public ip address: dig example.com are your ports 80 and 443 externally reachable, and is caddy able to bind to them? check your firewalls, port forwarding, and other network configuration. wait! before trying again, switch to let's encrypt's staging environment to avoid being accidentally rate limited. once you get everything else working, it's safe to switch back.