One way to speed up your wireless network is to let your modem or modem router support a network of 802.11 N devices. The majority of the gadgets nowadays support wireless N network, so it may be a good time to start phasing out your oldest equipment to take advantage of the new.
The reason why your network becomes slower is because when newer more advance router tries to do back ward support, it can actually hinder the performance of the entire network.
To counter this effect, you will have to upgrade all of your devices to 802.11N
It should be noted that you will be stuck with backward support if you are still using older devices. However, when this happens, you can consider to use hardwire connection for those older devices. Let all the newer devices stay on the 802.11 N Support Required network to improve their speed and performance.
After logging into your router, you should be able to find the same or similar options under your wireless options setting. For this example, we will use SBG6580 as it is a popular model.
It should be noted that when you turn on this option, all of your wireless devices that rely on the old 802.11g wireless devices will cease to connect.