Wireless network troubleshooter
Perform an initial connection check
In this step you will check some basic information about your wireless network connection. This is to make sure that your networking problem isn't caused by a relatively simple issue, like the wireless connection being turned off, and to prepare for the next few troubleshooting steps.
Make sure that your laptop is not connected to a wired internet connection.
If you have an external wireless adapter (such as a USB adapter, or a PCMCIA card that plugs into your laptop), make sure that it is firmly inserted into the proper slot on your computer.
If your wireless card is inside your computer, make sure that the wireless switch is turned on (if it has one). Laptops often have wireless switches that you can toggle by pressing a combination of keyboard keys.
Click the network menu on the menu bar and make sure that the Enable Wireless setting is checked.
Open the Terminal, type nm-tool and press Enter.
This will display information about your network hardware and connection status. Look down the list of information and see if there is a section related to the wireless network adapter. The information for each network device is separated by a row of dashes. If you find the line State: connected in the section for your wireless adapter, it means that it is working and connected to your wireless router.
If you are connected to your wireless router, but you still cannot access the internet, your router may not be set up correctly, or your Internet Service Provider (ISP) maybe experiencing some technical problems. Review your router and ISP setup guides to make sure the settings are correct, or contact your ISP for support.
If the information from nm-tool did not indicate that you were connected to the network, click Next to proceed to the next portion of the troubleshooting guide.