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Wireless Networking Issues



This article provides helpful information and links for basic wireless network troubleshooting. More specifically, this article focus' on 802.11a/b/g/n networks. This article does not cover Mobile Broadband (cellular based wireless) or Bluetooth (also known as WPAN).


Table of Contents

  1. Background Information
  2. Wireless Standards
  3. Troubleshooting
  4. External Articles

Background Information

The primary pieces of information needed for Wireless network troubleshooting are listed below.

  1. SSID
  2. Security Type
  3. Security Key or Passphrase
  4. Distance from the Access Point or Router
  5. Line of Site
  6. Channel Signal Overlap


SSID: The Service Set Identifier. This is the name of the network you're interested in joining. Wireless networks can be configured to broadcast this SSID, or to hide the SSID. If the SSID is broadcast, it will be listed in the "Wireless networks available". If the SSID is NOT broadcast, you'll need to know exactly how it is spelled and capitalized in order to join the network.

Security Type: This is the type of encryption used on the network to keep data secure. Windows may figure this out for you, but it's important to know what type of security is being used. This also controls what type of security key and passphrase you can use. The common options for security are listed below in order of their security level. No security is the least secure and WPA2 is the most secure.

  1. No security (also known as open)
  2. Wired Equivalent Privacy (WEP) 64 bit
  3. Wired Equivalent Privacy (WEP) 128 bit
  4. Wi-Fi Protected Access (WPA) options include AES and TKIP
  5. Wi-Fi Protected Access version 2 (WPA2) also including AES and TKIP



Security Key or Passphrase: This is the actual key used to encrypt the data. Without this key or phrase being correct, it is not possible to understand the data flowing across the network. This is basically like the secret knock or "open sesame" secret phrase.

Distance from the Access Point or router: The range of acceptable signal strength varies significantly between Wi-Fi types but a good rule of thumb is 120 feet indoors, and 300 feet outdoors.

Line of Site: Anything between the access point and the device will reduce signal strength and range. Some materials have more impact than others. Dense wood (such as oak) and metal have the most impact. Sheetrock and cloth have a very minimal impact. Utility closets, wood cabinets, metal piping and restrooms between the access point and the device will dramatically reduce signal strength.

Channel Signal Overlap: A Wi-Fi signal occupies five channels in the 2.4 GHz band; any two channels whose channel numbers differ by five or more, such as 2 and 7, do not overlap. The oft-repeated adage that channels 1, 6, and 11 are the only non-overlapping channels is, therefore, not accurate; channels 1, 6, and 11 are the only group of three non-overlapping channels in the U.S. Other Wi-Fi networks in the area on overlapping networks may be interfering.

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Wireless Standards

IEEE 802.11 a/b/g/n are the accepted industry standards. The features and strengths versus weakness' of these standards are shown here.

Standard Release Date Frequency Range Max Speed Realistic Speed Indoor Range Outdoor Range
802.11a 1999 5 GHz 54 Mb/s 23-28 Mb/s 50 ft 100 Ft
802.11b 1999 2.4 GHz 11 Mb/s 5.9 Mb/s 150 Ft 300 Ft
802.11g 2003 2.4 GHz 54 Mb/s 22 Mb/s 150 Ft 300 Ft
802.11n 2009 2.4 GHz & 5 GHz 300 Mb/s 130-150 Mb/s 230 Ft 820 Ft

The effective range varies dramatically based on Line of Sight and the materials through which the material needs to pass.
802.11a Signal Range Example. Notice how even a few walls absorb the signal.


802.11g Signal Range Example. Notice how the walls have dramatically less effect on the range.

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Troubleshooting

Please find below some troubleshooting steps for the following scenarios:


Scenario Troubleshooting Steps
SSID visible but cannot connect to it
  • Verify Encryption Type (WEP/WPA/WPA2) and Security Key/Passphrase
  • Verify that the SSID is standard and capitalized correctly using only letters and numbers
  • Reboot the Access Point (AP) / Router
  • Reboot the client (computer/printer/etc)
  • Verify that the Access Point/Router is within the realistic indoor range for the wireless standard it uses and that the client supports that wireless standard (e.g. both devices support 802.11n)
  • Verify the client can support the security type used by the Access Point or Router
No SSID's are visible
  • Verify that Wi-Fi is enabled (BIOS for computers, menu settings for printers and projectors)
  • If the system has a Wi-Fi switch, verify that it is in the On position
  • Verify that the Wi-Fi radio is enabled in the driver/management software
  • Verify that the Access Point/Router is within the realistic indoor range for the wireless standard it uses and that the client supports that wireless standard (ex. both devices support 802.11n)
  • Reboot both client device and the Access Point / Router.
Some SSID's are visible but the specific one you require
  • Verify that the Access Point / Router is set to "Broadcast SSID"
  • Verify that the Access Point/Router is within the realistic indoor range for the wireless standard it uses and that the client supports that wireless standard (ex. both devices support 802.11n)
  • Reboot both client device and the Access Point / Router.
  • Verify the client can support the security type used by the Access Point or Router
Can connect to the correct SSID but cannot obtain an IP Address

  • Certain information is required before troubleshooting this issue can begin.
  • 1. IP Address
    2. Subnet Mask Address
    3. Default Gateway Address
    4. DNS Server information
  • Do any of the devices have an APIPA address? (169.254.xxx.xxx)
    • Reboot/Restart the router or gateway
    • Check all cable connections and reseat making sure they are firmly in place.
    • Use ipconfig to release/renew the address
    • Navigate to the Command prompt:
    • Select Start and enter CMD into the Run search box
    • Enter the following at the Command Prompt:
      • > ipconfig/release
        > ipconfig/renew
  • Do all the devices have the same Subnet Mask address?
  • Do all the IP address's start with the same numbers (they're in the same range/subnet). For instance they all start with 192.168.1.x or 10.1.52.x
  • Make sure there are no devices with the same IP address. If there are, this will cause an IP conflict and 1 or both devices will fail to connect.
  • Use PING to verify an IP address is seen on the Network
    • Select Start and enter CMD into the Run search box

    • Enter the following at the Command Prompt:

  • > Ping

    192.xxx.xxx.xxx
  • If the IP address is seen and found, you will see 4 lines of replies showing the time taken to check the network connection (in milliseconds)
  • if you receive a "Request Timeout" message, either the IP address is not recognised or it cannot be found on the network.

Can connect to the network but cannot retrieve data

  • Verify SSID, Security type and Encryption Key / Passphrase
  • Delete the Network Profile and reconnect
  • Verify that the Access Point/Router is within the realistic indoor range for the wireless standard it uses and that the client supports that wireless standard (ex. both devices support 802.11n)
  • If possible, update Access Point / Router to the current firmware version
  • Update client device firmware / drivers
  • Reboot both the client device and Access Point / Router
  • Check if the client device can connect and transfer traffic on other networks.
  • If possible, Disable firewalls for troubleshooting purposes only.

Device Disconnecting from the Network Intermittently

  • Update firmware and drivers on both the client device and Access Point / Router
  • Move the client and Access Point / Router closer together
  • If possible, change the channel setting on the router. Channels 1, 6 and 11 are usually the best options.
  • Verify there is not a secondary program trying to manage the wireless adapter.
  • Adjust the antennas on the Access Point / Router to be perpendicular to the direction to the client (not pointing towards or away from the client)
  • Check if this problem happens on other wireless networks?
  • Log in to the router and check the "Uptime". If the uptime is always fairly short, the router may be rebooting and dropping all clients.
  • Reseat the wireless adapter on the client device.

Make sure the disconnects don't coincide with the use of other devices in the same frequency band. Examples include:

  • Microwave Ovens
  • Bluetooth devices
  • Baby monitors
  • Cordless telephones

Slow Connection speed

  • Try moving the client device to another location. The goal is to change the Line of Sight obstacles between the router and client.
  • Try moving the router to another location. The goal is to change the Line of Sight obstacles between the router and client.
  • If possible, change the channel setting on the router. Channels 1, 6 and 11 are usually the best options.
  • Update firmware and drivers on both the client device and Access Point / Router
  • Adjust the antennas on the Access Point / Router to be perpendicular to the direction to the client (not pointing towards or away from the client)

Eliminate other devices in the vicinity that use the same frequency band. Examples include:

  • Microwave Ovens
  • Bluetooth devices
  • Baby monitors
  • Cordless telephones.

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External Articles

For more information on Wireless Networking and Protocols, please see links below:

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文章 ID: SLN152089

上次修改日期: 07/07/2016 07:51 AM


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