A 523 error is a Cloudflare-specific error code for:
"Server isn't reachable."
This occurs when the origin web server has an issue and has become unreachable. The most common cause is that domain’s DNS settings are incorrect.
Error 523 typically occurs when a network device between Cloudflare and the origin web server doesn’t have a route to the origin’s IP address.
Please contact your hosting provider to confirm your origin IP and then make sure the correct IP is listed for your A record in your Cloudflare DNS Settings page.