I have a newly configured server with Windows Server 2012 on which I have added the Active Directory Domain Services to and created a new forest with a single domain tree. I also have a newly configured Windows 8 Professional box on the same network (2 switches, 1 wireless router that connects directly to a cable modem) and when I attempt to add the computer to the domain, it says that it cannot find or locate the Domain Controller for my domain. I tried this on a Windows 7 Ultimate box and it gave more information but basically related to DNS issues. Is there something special I need to do on the server or on the wireless router (DHCP) to allow my client PC's to find my AD server?
You should make your Domain Controller your primary DNS and DHCP server. Then, instead of using your router as these things, simply use it as the default gateway instead.