What kind of internet do you have? Fiber, DSL, or cable? I'm also wondering how your TV is set up as well. Is it hooked through a coaxial cable right into the modem? A picture of the modem might help.
Cable tv shouldn't require a modem under most circumstances. Unless you have fiber optic TV, which then converts digital signal of fiber back to analog signal through coaxial cable, which then hooks into your TV?