Before an AutoSSL provider can issue a certificate, it must verify control of the hostname. This process is commonly called domain-control validation (DCV).
Successful validation generally requires the hostname to use DNS and web routing that allow the validation request to reach the correct account. A hostname that points somewhere else, is blocked by restrictive DNS, or cannot be validated will not receive a certificate through that attempt.
When AutoSSL reports a DCV error, start with DNS: confirm the hostname resolves to the intended service and that its authoritative DNS is serving the expected records.
