SSL Cert keeps going back to self-signed

Now, I’ve experienced a 502 Bad Gateway error on the non-secure version of my website, and now when I visit the secure version, I find a “Your connection is not private” error to see my SSL Cert was “de-uploaded” and it is back to the self-signed. This has happened 6 times now, and now my website is completely inaccessible. I keep having to re-upload my certificate and I’m tired of doing it. This problem needs to be fixed.