I just had an issue where Cloud-flare thought my whole website was down. I was seeing 503 Service Temporarily Unavailable (cloudflare-nginx) pages for every page.
After some testing i noticed that this only happened after visiting a specific page. The page worked for the first load in a fresh browser. This particular page contained a script tag to a web socket server that we decommissioned a while back. This script was returning error 525.
The failure of this single script caused Cloud-flare to believe the whole website was down even though the missing script was on a different port.
My issue was fixed by removing the dead script tag, but It is not clear why this has only started happening today. It may be related to a platform update so i’ve posted this incase someone has a similar issue.