CiscoDPQ3212 is my modem. Is this adequate for hi speed wifi?
The DPQ3212 is a modem with digital voice adapter, it doesn't have WiFi built-in. It should support speeds up to Premier. If you want WiFi, you must add a router, I would get one with gigabit Ethernet ports & dual band supporting wireless ac.
Another option is to trade the modem for a gateway (combo modem/router) but that comes with a monthly rental fee from Cox.