I am having the same issue as well, error 521 every few minutes, working for a few after a refresh, then the error hits again. Using CloudFlare, and it’s only been happening as of the last 24 hours (when everyone else’s issue started to occur). I’m pretty sure it isn’t on CloudFlare’s end, “all systems are go.” CloudFlare support staff has also indicated to me that it’s an issue on the host’s end. I have one IP configured in the DNS -- the new server IP. I’m on x14, but that first make much of a difference since others are experiencing this across several of the servers.