We have put together a short survey to capture your feedback in terms of what BT can do when you experience home Wi-Fi issues. We would appreciate it if you could take a couple of minutes to complete a short survey. Read more from here, Fix my home Wi-Fi
Does your master socket have 2 sockets, one for phone and one for broadband like sockets 5,6 and 7 below. If so, it is filtered and you don't need a separate filter.