SSL not work on www.child.domain.com

Good morning, I have a small problem, when I request an SSL from Let’s Encrypt I get an error returned via email.

Failed to obtain SSL for: child.domain.it and: www.child.domain.it

Trying to obtain SSL for: child.domain.it

Successfully obtained SSL for: child.domain.it.

The domain www.child.domain.it is never protected by an SSL. I have also tried manually setting up a certificate from CloudFlare.

  • I have tried domain.it / *.domain.it (it is applied correctly to the main domain)

  • I tried with child.domain.it / www.child.domain.it

(It does not work and keeps telling me it is not protected - in fact the WP site does not load)