Hi @danilo_m
there is a check of your domain, ~~6 hours old - https://check-your-website.server-daten.de/?q=aulasprofdanilo.com.br%2Fmoodle%2F
http has a timeout. That may be a problem if users don't add https. And there is a small content problem you should fix (wrong inline images), but that's not a certificate problem.
-->> A screenshot with the problem is required.