[Nyx]

Do you mean increasing you internet speed more than what your ISP is giving you? As far as I know, you can't increase it further

Precisely.

If your ISP Is providing the maximum speed to your line/cable, and your equipment Is accommodating & delivering that (maximum) speed to your devices, then you cannot Increase It.

Only thing I can think of is if you're on a shared internet connection that isn't solely for your own use, you could just route more bandwidth towards yourself. Other than that the ISP entirely determines your speed. Could try SEing them as well.