The 10.0.0.0/8 is a private IP range, i.e.: not public. Therefore the Let’s Encrypt validation servers can’t connect to your server, which is required for validation. And no validation means no certificate.
The 10.0.0.0/8 is a private IP range, i.e.: not public. Therefore the Let’s Encrypt validation servers can’t connect to your server, which is required for validation. And no validation means no certificate.