setup: DVR hooked up to 2wire wireless modem router

i have a broadband connection using dynamic ip (PPPoe)

hooked up a dvr to 2wire wireless modem router

registered a dyndns DNS tagging it to my PPPoe ip address

setup up my DVR DDNS setting with my dyndns DNS account login and password

setup my 2wire wireless modem router with the correct port forwarding for DVR (disabled wireless function)

everything went on fine, enter url with the DNS and i was able to remote view my CCTV via DVR

but... in a event of power interrupted, 2wire modem restart and i cant remote view my CCTV anymore.

any solution or steps i have missed out.
or something i should take note about dynamic ip principle in order for my CCTV DVR remote view to be correct.

how do i ensure or set my DVR setting to auto update ip address in the event of PPPoe ip changes to dyndns account according so i can remote view with the dns i registered?

very troublesome to go down to site to check the ip address of the PPPoe and reset the dyndns DNS with the new ip address before it works again.

and some time i have to reset the 2wire modem and remove the port map application and redo and create a new port mapping for the DVR

please help... urgently...
site is too far and troublesome to go down each time modem got rebooted

thanks!