Usually one of these, no jargon needed:
- This domain hasn't been added as a proxy host yet, or it's under a different name.
- DNS points here (
A / AAAA / CNAME) but nothing inside claims it.
- A typo somewhere — an extra subdomain, a wrong scheme.
- The host exists but is switched off, or the certificate's still provisioning.
Got here by mistake, or think something's actually broken? I'd appreciate a report at jakub@sopel.dev