This article addresses both DrayOS and Linux based Draytek routers. Each latest OS supports DrayDDNS for Let’s Encrypt certification.
It is presumed that your DrayDDNS or registered domain has been successfully registered.
Also check that the [System Maintenance] > [Time and Date] current system time is synchronised with an NTP server or your browser.
Make sure that your DrayOS router is running 3.9.0 or higher firmware version that supports Let’s Encrypt certificate for DrayDDNS domains. If you need to activate your DrayDDNS service first, follow steps described in this article