Tips For Wireless Troubleshooting

[ChrisUlrich]

Locate access points 10 to 20 feet from microwave ovens: Microwaves use nearly the same frequency as the 802.11b specification.
Don’t let Bluetooth bite: Bluetooth specifies a way to attach peripherals to PCs. It’s designed to operate at short range. The specification uses the same frequency range as 802.11b. Small as the distance is, your user’s wireless PC or PCI card falls within that range. The IEEE is working on a specification (802.15) to reduce RF interference; in the meantime, Bluetooth for one may have to be sacrificed for the WLAN needs of the many. One option may be to get an extendable antenna for the wireless NIC.
Locate other sources of interference: If your users are having trouble connecting or connect at slower speeds, power up your site survey software or RF meter and investigate. You may have to relocate an access point, adjust antennas, or move some users’ computers.

• Make sure that your Wi-Fi adapter or mobile data card is properly connected and enabled.
• Make sure the Wi-Fi adapter is defined in iPassConnect and active. To verify on notebook computers, go to Settings > Connection Settings > WLAN and select the adapter from the device menu. To verify on Windows Mobile handheld devices, go to Start > Communications Manager > WLAN and ensure that WLAN button is not grayed out.
• Make sure the Access Point you are connecting to does not require 802.1x or WPA2 (which are not supported).

Driver Issues:
Out-of-date or buggy wireless NIC drivers can cause problems such as frequent disconnects or slowness, even when the device is close to an access point. Always check the driver version and date when troubleshooting wireless issues. If the driver is older than 6 months, chances are there is a newer version that can be downloaded from the device or NIC manufacturer. Intel Centrino wireless NICs are notorious for driver issues. Make sure you are running the latest Centrino drivers available.

Disable 3rd party wireless management software:
Check for 3rd party software (eg. anything that is not Windows) managing wireless and internet connections. If possible, disable this application by right clicking on its icon in the lower right hand side of the screen and clicking on disable or configure. If you choose the configure option, there should be a check box that says “allow windows to manage this connection” thus allowing Windows to manage your wireless connection. If the program can’t be disabled, you can try uninstalling the application, but make sure you have software CDs that came with your computer or wireless card (specifically, drivers). If you uninstall the application and it also removes the driver needed for your wireless device to work at all, just put in the CD and start it up. Try reinstalling just the driver without the entire software package, but if all else fails just install the whole package again.

Signal dropouts:
First, be sure you (and your close neighbors!) don't have 2.4GHz cordless phones or baby monitors in the house. This is the same frequency that Wi-Fi uses, and if someone is talking on the cordless phone, it will likely cause severe interference with your network. Cordless phones are available in several other frequencies, so just switch, or better yet, get rid of your landline altogether and switch your home number to your cell phone.
Second, check if the dropouts seem to coincide with the use of your microwave oven, or any Bluetooth devices, such as wireless mice, keyboards, and printers. These devices also use the same frequency as Wi-Fi, and can cause interference. Place your Wi-Fi router as far from them as possible.

Finally, check to be sure that your neighbors don't have competing Wi-Fi networks on the same or a nearby channel. In the U.S., Wi-Fi channels range from 1 to 11, each focusing on slightly different frequencies in the 2.4GHz radio band. But you can't simply set your router to channel 4 if your neighbor uses 3 and expect that to fix things. Wi-Fi channels overlap, just like those on your FM dial. That's why you see spacing between radio stations, and the bigger the station, the more space it takes up due to a stronger signal that spills over into neighboring airwaves.

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[SpearMan]

If RADIUS is working but the client's access requests are rejected, look for an 802.1X Extensible Authentication Protocol (EAP) or user login problem. Your client must support one of the EAP types required by your server and must supply a valid login and password / token / certificate or other kind of credential.
If your server requires EAP-TLS, select "Smart Card or other Certificate" on the client's Network Properties / Authentication panel.
If your server requires PEAP, select "Protected EAP" on that panel.
If your server requires EAP-TTLS, install a third-party 802.1X Supplicant program like Juniper OAC or Cisco SSC on the client.
Make sure that client and server EAP-specific properties match, including server certificate Trusted Root Authority, server domain name (optional), and tunneled authentication method (e.g., EAP-MSCHAPv2, EAP-GTC).
If you are prompted to accept the server's certificate at connect time, examine the certificate carefully, verifying issuer and identity. Never add an unrecognized or suspicious certificate to your trusted list.
If EAP-TLS problems persist, use Internet Explorer to inspect the client's certificate and make sure the certificate is valid (e.g., not expired).
If PEAP problems persist, use CHAP Configure to prevent Windows auto-logon and enter a valid username and password when prompted.
If you still haven't spotted the problem, consult your RADIUS server's 802.1X documentation for EAP configuration and debugging hints.