Configuring NTP server for a bridged DSL-N14u

Hi, after bridged my dls modem from Asus and putted a N66u as a main router I can't set the time from a NTP server in my modem.

I can't find where can I setup a gateway for my modem to internet and then, I supose, can't reach the NTP server to get the right time.

Any idea?

Thanks