The direct answer to whether this action reduces internet speed is yes, it typically does. The splitting process involves using a splitter. An internet splitter, also known as an Ethernet splitter or network splitter, is a device that allows you to connect multiple devices to a single internet connection. When the signal is divided, the available bandwidth is also divided among the split signals. This means that each device connected through a splitter will receive a reduced amount of bandwidth, resulting in slower internet. If there's a drop in performance, definitely call your ISP. Since cable is a shared medium, everyone in your building shares the connection, so the impact from one additional splitter.