What RealBeast suggests should work quite well. I did the same thing with a different ASUS router. I had been a DSL customer for years and replaced my Dlink router with an ASUS RT-N66U last summer to solve the multiple connection/streaming problems I was having with the DLINK. This worked perfectly.
Last month I switched to Comcast for higher internet speed. I got a Cisco/Xfinity as a leased modem. It worked fine, but I didn't want to pay the monthly leasing. I just replaced it with an Arris TG862. The Arris works fine for wired connections and supports the phone just fine, but has horrible WiFi. I reconfigured my ASUS as an AP (Matched the IP scheme, turned off DHCP, Ethernet to Ethernet connection. No crossover cable needed) The nice thing about a third party solution from ASUS and many others, is that they support a guest SSID, to let visiting friends access the internet, while keeping them off of your home network, not to mention more overall control with all Wif settings, if you want to tweak things.