No internet on Cisco 800 Router

Hi,

I’ve recently bought a Cisco 887 router/modem.

Now I have a problem with accessing the internet with my clients.

I’ve setup the Dialer (WAN tests are good). I also get a WAN-IP form my ISP. My internal LAN is also working good.

Now is my problem that I cannot get internet on the LAN-clients.

Maybe i’ve forget something to setup, but I do not have any idea what is missing in the configuration.