Thanks for your help. To clarify, this is a production deployment of a small WordPress site on a VPS server. Traefik manages TLS certificates and forwards HTTP traffic to HTTPS. WordPress and plugins use the loopback interface for various things, including its internal REST API and scheduled tasks. I found certain downloads that generate a PDF performed poorly and site health reports an error by default when it fails trying to access its own container’s port 443, as it only listens on port 80.