If it is a wireless router, then it needs to supply ipaddresses on a subnet for the wireless clients and route them to the SME wired LAN. If it's an access point, it can parse the ipaddressing from the SME OK.
Put it in AP mode, and let the box get it's dhcp from SME as well and all will work fine. i normally enter the AP's MAC address into SME hostname and gve it a fixed IPadrress in the SME subnet.