My BT Home Hub 3 is located in my office. Along with its wireless, it's connected to a wired network that runs into a number of rooms of the house. One of those rooms is about 15m and 4 walls away from the hub meaning that the wireless signal to that room is extremely poor. I want to improve the wireless into the room. As said, it has wired ethernet into the room with one free ethernet port (the other being plugged into my home server). What's the most cost-effective equipment to do this with, keeping everything on the same network?