Hi,
Using the DIR-655 with OpenDNS and DNS-O-Matic is a great way to increase your Internet browsing speed and use other features offered by OpenDNS. I use their content filtering making sure my kids can't get to inappropriate sites.
The DIR-655 can take care of this directly using the Dynamic DNS settings. Otherwise you would have to run a client on one of your computers in your network to update DNS-O-Matic when your IP changes.
Set the router to use OpenDNS in the DNS fields on the WAN settings page. Set up a DNS-O-Matic (https://www.dnsomatic.com/) account and add a service for OpenDNS, Finally under Dynamic DNS on the router set the following:
Server Address: updates.dnsomatic.com
Host Name: all.dnsomatic.com
Username or Key: Your user name
Password or Key: Your password
Verify Password or Key: Your password again
Timeout: 576
After you have saved the settings make sure you get a "connected" status message on the Dynamic DNS page.