How to Connect between UT Starcom 3002g4 and Cisco Router 1721

Hi,

I have a Wireless Router WA 3002g4 in PPPoe mode which connects me to internet directly plugged into switch. As well, I have Router Which Connects me to Private Network and Assigns IP using DHCP to all the systems which also Connects to the Switch.

All my systems connect to the internet using a gateway which is the IP address assigned to the WA 3002g4 Router for Internet. But when i configure my system to DHCP Mode, the internet Connection is lost. Can any one help he in Creating a link between both the routers.

Thanks.