If your router doesn’t have a build-in feature to update dynamic DNS records you will have to use a software client that runs on one of your computers. The Linux tool ddclient already comes packaged in the Ubuntu repository and very easy to install. See also DynDNS’ knowledge base artcicle.
daemon=600 # check every 600 seconds syslog=yes # log update to syslog mail=gerrit # mail all messages to gerrit mail-failure=gerrit # mail failed update messages to gerrit pid=/var/run/ddclient.pid # record PID in file cache=/tmp/ddclient.cache # cache file # use DynDNS' checkip-service to determine IP use=web, web=checkip.dyndns.com/, web-skip='IP Address' protocol=dyndns2 # default protocol server=members.dyndns.org # default server login=my-username # DynDNS username password='my-password' # DynDNS password my-dyndns-domain.dyndns.org wildcard=YES