Use this checklist as a guide to Wi-Fi troubleshooting. It's geared toward internal Wi-Fi adapters / modules  in Toshiba notebooks, but some of the advice applies to any Wi-Fi adapter.

1. With an internal Wi-Fi adapter, make sure that the wireless antenna switch on the PC is turned ON. See the User's Guide for your computer model for the location of this switch.

2. While testing, turn off MAC address filtering and WEP on the Wi-Fi access point. Also make sure that SSID Broadcast is enabled on the Wi-Fi access point.

3. Make sure that the SSID for the Wi-Fi adapter is correct. SSIDs are case sensitive, and must exactly match the SSID that is set in the access point.

4. Check the access point's configuration. Specifically, make sure that Short Preamble is NOT enabled.

5. Update the access point's firmware. Many problems can be eliminated by doing so.

6. Install the latest firmware and driver for the Wi-Fi adapter. Many problems can be resolved simply by updating the firmware, the driver, or both.

7. If the Wi-Fi adapter was working correctly until the installation of a new version of its driver, re-install the earlier version of the driver. If the computer is running Windows XP, use the Roll Back Driver feature in Device Manager.

8. Check Device Manager to be sure that the channel listed in the properties page of the client is the same as being used by the access point.

9. Verify that Network Connections indicates that the network connection is enabled.

10. If the Wi-Fi adapter is an Agere product, and Windows 2000 is installed, install the Registry Key for Agere MiniPCI WiFi adapter for Windows 2000.

11. If the Wi-Fi adapter is a PC Card, and Windows 2000 Service Pack 3 is installed, see the following Microsoft Knowledge Base article: http://support.microsoft.com/default.aspx?scid=kb;en-us;327947

Terms used in this document:

• Access point (AP) A Wi-Fi access point is required for Wi-Fi network connections. The access point can be a stand-alone unit, or a combination access point and router (sometimes called a "wireless router").
  
  
• WEP Wired Equivalent Privacy is an encryption scheme that helps keep data on your wireless network secure. Using WEP is preferable to having no encryption, though stronger authentication and encryption standards are under development, notably 802.1X.
  
  
• SSID (Service Set ID) refers to the name of your wireless network. Short for Service Set ID, the SSID identifies your wireless network. The SSID is set in both the access point configuration, and in the connection properties on the PC. The SSID is case sensitive, and the SSID you set on the PC MUST match the SSID of the access point.
  
  
• MAC Address, or Media Access Control Address is a unique ID (commonly, a 48-bit hexadecimal number) assigned to every network adapter, during the manufacturing process.
  
  
• MAC address filtering (also called Access Control) allows configuration of the Wi-Fi access point to limit access to specific Wi-Fi adapters (and thus the PCs that contain them).

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