You should lock down your wifi router to prevent people intruding on your network and taking your bandwidth and or data.
You will need to log into your router by entering the routers IP address into your web browser.
You do this by connecting your router to your computer with a network cable then entering the address into a browser to access the router.
Most routers use an address like 192.168.1.1, 192.168.0.1 or 192.168.2.1 are also common.
Check your manual or Google to determine the correct IP address.
Change The Router Passwords
First change the router passwords , default router passwords like "admin" are easy to remember, but are also common knowledge.
No password is perfect, however a better password can be used by combining numbers and letters and avoiding words from a dictionary.
Change your Wi-Fi password as well as your router administrator password
Next Change Your SSID ( your wireless network name)
Wireless network's have a name, known as Service Set ID (or SSID).
The simple act of changing that name discourages people from targeting you.
Wireless networks with default names such as "Belkin" will probably not have custom passwords or encryption.
Turn On WPA2 Encryption
Go into your wireless security settings and turn on WPA2 encryption with an approprite password as I have discussed above.
Turn On MAC Filtering
Every device that accesses the Internet has a Media Access Control (MAC) address, which is a unique identifier composed of six pairs of alphanumeric characters.
You can limit your network to only accept specific devices by turning on MAC filtering, which is also a great tip for optimizing your wireless network.
How do you find your MAC Address?
On Windows , open a command prompt by selecting Run from the Start Menu, type cmd and hitting Enter
Windows 7 users type cmd in the Start Menu search box.
You will now see a command prompt
Type ipconfig /all at the command prompt and press Enter to bring up your IP settings.
Your mac address will look like the following 05:0c:ce:e2:6c:28
Mac OS X, go to System Preferences and Click Network.
From there, Select "Wi-Fi" from the list in the left-hand column ("Airport" in Snow Leopard or earlier), then click "Advanced" , then look for the "Airport ID" or "Wi-Fi ID".
Smartphones , tablets , printers , check your manual or Google it.