DNS problems with WNR3500v2

Hallo,

I'm using my router as a DHCP server and it worked pretty fine until today morning. A week ago, set up a new Windows Server 2012 Essentials in the same network. The server is in the DMZ of the router and since it has Active Directory configured it is also running a DNS service.

The first problem was that the DNS server tried to use the router for forwarding DNS requests, instead of the 2 DNS servers defined in the router config. I changed it, now its working fine, but devices which are not in the domain (smart phones, netbooks, ...) couldn't access the internet any-more - starting from today morning.

I checked the DNS config and saw that the router is set as primary DNS service. I changed it manually to use the DNS Services which the router uses on its own, and it worked but it is more of a workaround than a solution.

Is it somehow possible to define what information the dhcp server on the router should send to the clients? Or is it default that the router works as a DNS Server - in this case, why did it stop working??

thx
Regards,
grJoe