It is important to realise that a range extender amplifies your Wi-Fi signal so it travels farther (in your home, for instance). A range extender does not speed up or improve your Wi-Fi signal. With today's technology, wireless connections are not full duplex. This means that Wi-Fi cannot transmit and receive simultaneously; the communication goes back and forth. This means that the speed of the Wi-Fi signal from your range extender is halved. In practice, this is usually not a problem; a connection to the internet is often so fast that reducing it by half does not result in a noticeable loss of speed. It only leads to problems for specific applications, such as streaming HD movies. However, even in this case, other factors come into play. If your router can handle speeds up to 150 Mbps and your range extender speeds up to 300 Mbps, the 50% speed reduction will have no impact on your network.