Troubleshoot Wireless Issues

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When troubleshooting wireless networks, as with cabled links, you need to consider problems with the physical media, such as interference, and configuration issues.

• radio frequency (RF) signal from radio-based devices weakens considerably as the distance between the devices increases
• If you experience intermittent wireless connectivity, slow transfer speeds, or inability to establish a connection
  • try moving the devices closer together
• If you still cannot obtain a connection
  • check that the security and authentication parameters are correctly configured on both devices

Troubleshooting Wireless Configuration Issues

• If a user is looking for a network name that is not shown in the list of available wireless networks (SSID not found)
  • user could be out of range
  • SSID name broadcast might be suppressed
    • the connection to the network name must be configured manually on the client
• Another factor to consider is standards mismatch
  • If an access point is not operating in compatibility mode, it will not be able to communicate with devices that only support older standards
  • when an older device joins the network, the performance of the whole network can be affected
  • To support 802.11b clients, an 802.11b/g/n access point must transmit legacy frame preamble and collision avoidance frames, adding overhead
    • if possible, upgrade 802.11b devices rather than letting them join the WLAN
  • Both 802.11g and 802.11n/ac/ax are more compatible in terms of negotiating collision avoidance
• consider that not all clients supporting 802.11n have dual-band radios
  • If a client cannot connect to a network operating on the 5 GHz band, check whether its radio is 2.4 GHz-capable only

Received Signal Strength Indicator

• wireless adapter will reduce the connection speed if the received signal strength indicator (RSSI) is not at a minimum required level
  • RSSI is an index level calculated from the signal strength level
    • E.g., an 802.11n adapter might be capable of a 144 Mbps data rate with an optimum signal, but if the signal is weak, it might reduce to a 54 Mbps or 11 Mbps rate to make the connection more reliable
  • If the RSSI is too low, the adapter will drop the connection entirely and try to use a different network
  • If there are two weak networks, the adapter might “flap” between them
  • Try moving to a location with better reception

Troubleshooting Wireless Signal Issues

• if a device is within the supported range but the signal is weak or you can only get an intermittent connection,
  • there is likely to be interference from another radio source broadcasting at the same frequency
    • try adjusting the channel that the devices use
  • Another possibility is interference from a powerful electromagnetic source, such as a motor, or a microwave oven
  • there might be something blocking the signal
    • Radio waves do not pass easily through metal or dense objects
    • Construction materials, such as wire mesh, foil-backed plasterboard, concrete, and mirrors, can block or degrade signals
  • Try angling or repositioning the device or antenna to try to get better reception
• Wi-Fi analyzer software is designed to identify the signal strength of nearby networks on each channel
  • shows the signal strength, measured in dBm, and expressed as a negative value, where values close to zero represent a stronger signal
  • will show how many networks are utilizing each channel
  • Setting the network to use a less congested channel can improve performance