ARD, DynDNS and Airport Utility

The Sitch:

I'm trying to use Apple Remote Desktop via the internet to login to my Dad's computer.
He is using a Time Capsule and my Dad's provider is CenturyLink, who change their dynamic IP very often.

While I've read that DynDNS does not work well ARD and Airport does not work well with DynDNS. Thus, I edited CenturyLink's ZyXEL 660R-D1 DSL DynamicDNS configuration to point to my DynDNS account. I then changed my Time Capsule to Bridge Mode and Port Mapping to ARD or 3283 and 5900.

I am still not able to remotely login! Does anyone have any idea what am I ding wrong?

Thanks

Easiest solution is to just use Logmein.com. It is free, and there is a small client that goes on the computer you wish to remote to.

I have 16 computers I log into remotely through Logmein.com on a weekly basis for troubleshooting and maintenance. I can do it from my MBP or iPad.