This document describes the steps to configure the DDNS Client via LuCI to use Hurricane Electric's Free DNS Service. In this example I will show the steps to configure host.example.com domain to update with your router's public IP address.
Login to your registrar or edit your DNS Zone file to add the NS records for host.example.com to point to ns2.he.net through ns5.he.net (4 NS records total).
On your OpenWrt router under Services > Dynamic DNS enable the service with this configuration:
Save and Apply.
That should do it. If the above is useful and you use Hover to register a domain you can toss the author a buck credit with this referral link: https://hover.com/hUyus9hH