Dynamic DNS (DDNS or DynDNS) is a method of automatically updating a name server in the Domain Name System (DNS), often in real time, with the active DDNS configuration of its configured hostnames, addresses or other information.
Step 1 : configuration > Management > Dyndns > Add > Enable services
Step 2 : Select provider there was multiple provide also available
Step 3 : Method it will reach the communicate the dyndns provider in this USE WEB or Default route interface IP
Step 4 : Mention the Dyndns server ip where u host and enter the credentials
Step 5 : In Dyn record name mention the create the dns name for reach the server