There are several factors that can affect communication in a WLAN network. They are:
Radio Frequency (RF) interference
Firmware and hardware problems
Improper antenna alignment
To resolve this issue, perform these checks:
Ensure there is no RF interference that may affect the WLAN communication.
The sources of RF interference must be identified and eliminated. Alternatively, try to use a different channel which does not have RF interference. Spectrum analyzers are devices that identify and measure the strength of interfering RF signals. The Carrier Busy Test utility on the Cisco Access Point (AP) and bridges can also be used to check the radio activity on bridge channels.
WLAN does not work if there is a configuration mismatch between the wireless devices in a WLAN network. Parameters to check include Wired Equivalent Privacy (WEP) keys, Service Set Identifier (SSID), Channel used for WLAN, Data Rates, and Distance.
Use the Link test to check radio communication with a remote device.
The Link test sends data packets of a specified size to a destination radio, receives the same data packet back from the destination, verifies the data, and provides status information. For more information on this test, refer to the Performing a Link Test section of Antenna Basics.
WLAN adapters (wireless card) / ACU (Aironet Client Utility)