Both yes and no. A modem cannot make your internet connection faster than what your package allows. However, if your modem's maximum speed is lower than your internet plan's, your connection will be slowed. Take, for example, a 250 Mbps internet subscription. Your full plan speed will be 250 Mbps if your modem supports up to 350 Mbps, but not more. If your modem only supports 150 Mbps, the maximum speed you'll see is 150 Mbps, not 250 Mbps.