If you are renting your cable modem from your local ISP (Like Concast) then you are probably paying too much and you are not operating at “full” speed.
Test have shown that a ISP provided cable modem operates at half the speed of a store bought modem.
Also noteworthy is the fact that you can get a better modem for less cost then that of your service providers equipment.
Lastly, do not let a cable tech tell you that he can not operate on your equipment. THEY CAM![SOURCE](http://www.reddit.com/r/LifeProTips/comments/27rfgy/lpt_dont_rent_a_modem_router_from_your_isp/)