Debug WLAN Client Connectivity Issues

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How To Debug WLAN Client connectivity Issues:

Debugging is a Skill which every Test engineer should have and everyone has there own style of doing it. A same approach might not be the best approach for every problem. Also, it is very much dependent on the resources available at that moment.

Lot of beginners have this question as "How to Debug". Well, you learn the answer based on your own experience and if you have a great team, they will share their experience. As they say, " A smart person learns from his mistakes, but a smarter learns from others". A good team is one which shares their learning with their peers and create that culture of sharing knowledge.

As part of this Blog I will share some pointers that I have learnt with my experience and I am open to any sort of comments. Since most of my career till now has been with testing WLAN clients, I will restrict this to debugging WLAN Clients and not AP/Infra.

Scenario 1 - Device not connecting:

Try connect with a reference device ( A reference device, is not a DUT but a device which is known to be stable ). If the reference device connects, we know that the DUT has a problem and is not related to AP/Infra/Environment
    • Check the WLAN config on client ( Password, Radio status, Country code, WPA/WPA2 setting )
    • Check Supplicant/Driver Logs ( see for crashes, Tracebacks, errors etc )
    • If Sniffer is available, then sniff the wireless captures and see at which point is the connection failing. 
      • Is it failing at association? Check reason code for association failure
      • Is it failing at 4-way handshake? Check Password.
      • Is it failing at EAP exchange? Check if AP/controller is added in Radius server. Verify if the Shared secret is correct. Check if time on Device is correct. Check if the certificates are valid. Check is Username/Password are correctly included in Radius Server. Check if Device has correct Username Password. Check if EAP type is supported by that radius server... etc..

Scenario 2 - Device Unable to Roam:

  • This depends on a lot of factors, whether the APs are placed at proper distance for the client to roam. 
  • Whether proper Roaming configs are placed in AP and on Client.
  • Go through Device Logs to know more info about the failure reason and get clue for the failure.
  • Go through Wireless Capture, and see at what point is the device roam failing.


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