How turn turn of WiFi on cable modem

First let me clarify some verbiage. Anything that has wireless is not a modem, but a gateway, which is basically a router and modem combined. I don't just say this to nick pick, but because if you have a router, you don't need the other router in the gateway. They will conflict. Your three options are;

1. Trade in for, or buy, a stand alone modem. Some examples would be the Motorola SB6141 or the Cisco DPC3010. 

2. Put your gateway into bridge mode. Only some gateways are capable of this, and how you do it depends on the gateway. What gateway do you have? What this does is turn off all the router functions in the gateway.

3.Put the router in AP mode. This takes all the routing function of the router, and turns it into a wireless access point(AP). You could use the new router for wireless, but all the routing (DHCP, NAT, Firewall, etc) would be done at the gateway. 

Okay this so called"gateway" is way too slow for gaming and thats why i bought a router which is giving me 58 mbps while the gateway was giving me somewhere 3.8 mbps. I currently have the "DPC3825" gate way and i would like to go to option 2 you provided. 

Unfortunately there is no way to bridge the DPC3825 as seen in this forum post. That feature has been disabled in that model. Did you rent or buy the gateway? I would suggest trying to trade it in for a DPC3010, which is basically the DPC3825 but without the router. 

This gateway was bought. I guess i would have to buy a new one.... ***

Where did you buy it from? Can you get a refund or exchange it for the device you need? The DPC3010 is actually cheaper, so you should come out ahead. 

I probably can't get a exchange/refund. My dad bought it last year at the COX store I believe. I'm pretty sure we don't have a receipt for it. Oh wellz