Error 521 using nginx on synology as a host

Hi everyone,

Let me preface that I have checked community tip #521 and am still confused as to why this isn’t working.

I’m running a home server on my synology NAS using docker and that’s where my nginx and all services are hosted.

My NGINX has a wildcard ssl certificate for my domain ( But when I type “” or “” I get an error 521 saying the web server is down.

My SSL settings on Cloudflare are set to full and putting them on flexible doesn’t work either.

Any help would be hugely appreciated

I assume that your NAS is behind a firewall/router? If so, then have you forwarded the ports on your firewall to your services. If you have, then what happens if you try an connect with the IP?