Random Outage Maybe SSL?

I had a staging site setup and hadn’t deployed to it for a about a week or two it randomly gave me 405 from cloudflare saying my server was down. I reporovisioned and redpolyed and it is back.

Anyways to determine what was wrong after the fact?

Could it have been a ssl certificate, how do I make sure the ssl’s stay up to date, I chose letsencrypt in the config.