Are you looking to encrypt your traffic so that people connecting to your network must enter a key/password? Or are you trying to secure the management interface on your router so that others cannot configure it? What model is it?
To set up a network key (password to access the network), follow these steps:
Open your browser and go to 192.168.0.1 Depending on your router's model number, the username/password combination will be different. Try admin/(blank), admin/admin, or user/(blank), where (blank) is not putting in a password at all.
If you look through the tabs and option pages, you will see a section for WEP or Network Key. A 64-bit WEP key is enough, you do not need a 128-WEP or a WPA key.
Make sure you apply the settings before closing the page.
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