Well maybe you got it running well for you then the way you have it.
Most preferred network platforms are to have a dedicated ISP modem, with out router built in.
Then have a dedicated router, like the 655.
Then maybe have extenders or relays like DAP units to help extend the range of the WiFi.
Most Dlink routers I've worked with are just meant to work as the main WiFi station and attach other relays or APs too.
My 2 cents.