502 Bad gateway ONLY on HTTPS
Super new here so please bare with me!
( This thread appeared to be similar to my problem but perhaps not quite: https://www.digitalocean.com/community/questions/nginx-reverse-proxy-502-bad-gateway-only-with-https )
I have recently moved a bunch of WP sites to a droplet running alongside Server Pilot. Everything runs perfectly and I'm very happy with DO - the only issue is two of the domains HTTPS addresses return these 502 Bad Gateway errors.
All the sites go through Cloudflare (SSLs are from Cloudflare), so all settings are viturally the same. The errors are showing as the Cloudflare branded error page, rather than a plain text Nginx error page if that makes any difference.
Any ideas what is going on here? All other sites work fine and the HTTP versions of the two problem sites work fine also. My first thought was to remove them from Cloudflare and then rescan/readd to Cloudflare. The error showing as server side got me thinking about checking here first though.
Any help appreciated.