Windows clients unable to access the net

I have a windows 2000 network consisting of two lan’s connected by two modems with an ADSL web connection on one subnet. The problem is that clients on the subnet without the ADSL connection cannot recieve data from the web, but the server can. Although the clients can ping and send requests to the internet. Their is a Windows 2000 server at both end providing routing services. Has anyone encounted this problem before.

Any help would be appreciated.

Thank You

Matthew