Best Practice - Keep Port 80 Open - Let's Encrypt
https://letsencrypt.org/docs/allow-port-8024.01.2019 · We occasionally get reports from people who have trouble using the HTTP-01 challenge type because they’ve firewalled off port 80 to their web server. Our recommendation is that all servers meant for general web use should offer both HTTP on port 80 and HTTPS on port 443. They should also send redirects for all port 80 requests, and possibly an HSTS header (on …