A test authorization for clases.canariaseducacion.org to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
DNS problem: SERVFAIL looking up TXT for _acme-challenge.clases.canariaseducacion.org - the domain's nameservers may be malfunctioning
The current status as reported by the Let's Encrypt status page is Service Disruption as at 2021-04-18 06:44:15.912 +0000 UTC. Depending on the reported problem, this may affect certificate issuance. For more information, please visit the status page.
https://letsencrypt.status.io/