Wi-Fi is a technology used to connect compatible devices to a private network using radio waves.  A compatible Wi-Fi device is any device that follows the Wi-Fi Alliance IEEE 802.11 standards.  Currently Wi-Fi uses two radio frequencies, 2.4GHz and 5GHz to establish communications between wireless access points and wireless clients.

Even though Wi-Fi serves a convenient way to establish a connection to a private network and/or internet, it is not without flaw and/or limitations. There are many variables to take into consideration when using Wi-Fi technology.  Because traffic is carried over the air an intruder can easily sniff out the packets transferred to and from your computer, encryption can be enabled on the Wi-Fi to encrypt information between the access point and client to secure your data communications but this still doesn’t prevent an intruder from sniffing out the packets, they will not be able to read them but they can still collect them.

There are a limited number of radio spectrums and operating channels that can be used (2.4GHz and 5GHz radio spectrum and operating channel 1-11 in the US).  Because of this limitation there is a higher chance of Wi-Fi interference which will impact communications between an access point and associated clients.

This document will provide troubleshooting techniques to tweak the Wi-Fi setting for CenturyLink routers to provide optimal wireless performance and security.

Note:  PK5001Z only support the 2.4GHz wireless spectrum.

Change Wireless Security

By default CenturyLink branded devices use a WPA/WPA2 mixed security mode.  Some wireless clients may have problems associating with wireless networks using a mixed security mode, changing this option to use one or the other (depending on client capabilities) will allow the client to associate the connection to the Wi-Fi.  To change the wireless security:

1. Open a web browser and go to http://192.168.0.1 to access the web configurator.
   
2. Do the following:
• Enter the Administrator Username: admin (default)
• Enter the Administrator Password: (located on the bottom of the modem)
• Select "Apply".
  
3. Select "Wireless Setup".
   
4. Select "Wireless Security" from the left pane menu.
   
5. Select the SSID you want to edit from the dropdown.
   
6. Select the security type you wish to use.  We strongly recommend using WPA2-Personal, this is the most secure encryption method available today, however, the selection should be based on what your wireless equipment supports.  You will need to do research on the wireless devices you own and what they support.
   
7. If using WPA2-Personal for the security type, select the AES option for encryption type.  If using WPA-Personal for the security type, select TKIP for the encryption type.
   
8. Select the "Default Key" or use your own by selecting "Use Custom Key".  Since the default security key is printed on the label under the router, we recommend setting a custom key.
   
9. Select "Apply" to save the changes.
   

Changing Radio Settings

The 2.4GHz wireless spectrum is widely used in different technologies such as Wi-Fi, Bluetooth, cordless phones, microwave ovens, garage door openers, etc..  These devices will create interference and negatively impact wireless performance.  Wireless range and throughput will decrease if there is too much interference on the specific operating channel.

To get a better picture of what the interference levels are like in your environment would require special equipment, which is costly.  A low cost way to check for Wi-Fi interference would be to use your computers Wi-Fi card and third party software to scan the 2.4GHz Wi-Fi spectrum. Keep in mind that going this route will not show what type of interference levels your environment is getting from cordless phones, Bluetooth devices or microwave ovens, the wireless card in your computer can only detect Wi-Fi signals.  Based on the readings you get from the third party software Wi-Fi scanner, you can determine which channel will be best to use. The Wi-Fi scanning software will provide info such as the SSID, security method being used by the Wi-Fi, operating channel, strength of the signal, etc..

If you are on a Windows computer you can use command prompt to get a printout of the current Wi-Fi signals, operating channel and signal level as well but this is only a printout.  The third party software will show any fluctuation on the signal strength and other setting in real-time. The commands to show the site survey printout are as follows:

C:\>netsh
netsh>wlan
netsh wlan>show networks mode="bssid"

To change the operating channel on the wireless router:

1. Click on the “Wireless Setup” menu option on the top of the web configuration screen.
   
2. Select the “Radio Setup” option from the left pane menu.
   
3. Set the appropriate operating “Channel” to use.  The auto detect option allows the router to automatically scan the 2.4GHz spectrum for the best channel but using this feature will drop all wireless associations while the operating channel is being changed.  To minimize dis-associations it is recommended to use a static wireless channel.
   
4. Select the “Wireless Power Level”, this refers to the amount of power the router will supply to the wireless radio.  Lowering the power level decreases the range of the wireless broadcast.
   
5. Select the 802.11 wireless mode you wish to use.  By default the router is set to 802.11b/g/n.  If you wish to only allow devices supporting 802.11n speeds you can make this change.
   
6. If you selected an 802.11 mode which used 802.11n, you will receive an option to select the aggregation you want to use for the packets.
• MPDU (MAC Protocol Data Unit) – Wraps frames in 802.11n MAC header, efficient in environments with high error rates.  Because all frames are wrapped in 802.11n MAC header packets are larger.
• MSDU (MAC Service Data Unit) – Wraps Ethernet header, which are shorter than 802.11n header, into a single 802.11n frame making the link more efficient.
• Disable – Turns OFF aggregation.
  
7. Set the MIMO power save state.  This option is also a feature of 802.11n to conserve power whenever possible.  Disable this option to have the router provide constant power to the antenna array.
   
8. Click the “Apply” button to save the settings.
   

Troubleshooting

• Unable to establish a wireless connection?
• Disable wireless security
• Change the SSID to rule out special characters being the problem
• Make sure firmware on router is up to date
• Try different wireless channels to make sure it is not wireless interference causing the problem.
• Make sure the wireless card drivers are up to date.  (This would involve the user checking the computer manufacturer's website, or the wireless card chipset manufacturers website for updates)
• Change the 802.11 mode.  (Legacy wireless cards may have a hard time connecting to a wireless network using 40MHz channel bandwidth used by 802.11n/ac)
• Slow wireless speeds?  Multiple variables can cause a slow connection.
  • 802.11a – speeds up to 54Mbps
  • 802.11b – speeds up to 11Mbps
  • 802.11g – speeds up to 54Mbps or 108Mbps using MIMO (multiple-input, multiple-output)
  • 802.11n – speeds up to 600Mbps*
  • 802.11ac – speeds up to 6933.3Mbps*
    Note: 802.11n has a feature that cuts the link speed in half if there is another 802.11n broadcast in the area.  So a router that supports an 802.11n connection up to 300Mbps will be cut in half to 150Mbps.
    *depending on spatial streams (antenna array)
• Check what 802.11 technology the client computer is using on the connection link.
• Check the speed at different distances, this will always be a factor.  Also, if using wireless technology with 40MHz bandwidth and higher, speeds will be fast at close range but wider channel bandwidth will be greatly impacted at farther distances. (802.11ac uses Beamforming to help maintain high speeds at great distances)
• How is the speed being tested?  The size of the packets used, protocol type, hardware and/or software can impact results. If the test is being run/ran against an online server, verify the internet speeds from the ISP by bypassing all networking equipment and connecting directly to the ISP modem.
• Are speeds identical across all devices?
• How many clients are connected to the Wi-Fi?  We do not recommend connecting more than 12 wireless clients on residential access points.  The wireless connection throughput is shared among all connected devices, the more devices connected the lower the throughput.
• Try different wireless channels to rule out wireless interference causing the problem.
• Wireless signal output range is low?  Multiple variables can cause a low signal output.
• Building materials – the denser the material the more it obstructs the signals flow.
• Antenna gain and Wireless radio output power will impact the distance the signal can cover.  The higher the gain of the antenna the greater distance that can be covered, but you cannot place a higher gain antenna than what the wireless radio can support. If the antenna gain is too high the wireless radio may not be able to supply sufficient power.  Changing the antennas can improve signal output, if antennas are external and removable.
• Position of the antennas – depending on the antenna (whether Omni-directional or directional) can impact the signal if pointing the wrong way.  Wireless routers and access points with internal antenna don’t really suffer from this.
• Wireless Interference – the greater the interference from neighboring Wi-Fi access points or other equipment overlapping the 2.4GHz spectrum the lower the signal output.  Change wireless channels or do a survey (wireless survey) of your environment to see what channel has the least interference for use.