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Wireless Devices 'Dropping Off' the Network

SamFickling

Setup:
Hardware: SG135
Software: UTM v9.705-3
APs: 2x AP55s
Non-Standard Config: AP Country set to US (not to my actual location), for hardware compatibility reasons

Problem:
For at least the last year, wireless devices on my network have been intermittently 'dropping off' the network.  This happens to single devices at a time, but multiple devices of different types from different vendors and different OSs are affected (ie; phones, tablets, laptops, TVs, set top boxes etc...)

What I mean by 'dropping off' is:

  • The device shows as connected to WIFI
  • The WIFI signal indicator on the device often shows with an '!' and says 'Connected, but Internet not available'
  • It is not possible to ping another device on the LAN or elsewhere
  • On the firewall, the status of the device shows as 'Online', with good signal strength & often good speed (but often this subsequently drops down to 24mbit)
  • According to the firewall log, a device which has 'dropped off' still registers as sending packets to the net
  • Physically moving the device to try to get a 'better' signal has no affect
  • Wireless logs sometimes show the last entry for the device as 'disassociated due to inactivity', but not always; sometimes the device has not disconnected according to the logs
  • The device can stay in this state for many hours and generally you must 'disconnect and reconnect' from the wireless to fix it, which almost always works.


Troubleshooting Steps Taken:

  • I am unable to pinpoint the exact time that this issue started, however there have been no hardware changes and was not a problem for many years prior
  • I have been unable to find any evidence of consistent issues in the wireless logs which may explain this or point to a common problem
  • There are no related issues shown in other places such as the Intrusion Protection or Advanced Threat Protection logs or anywhere else I can find
  • I have observed no patterns to this issue and it appears to affect virtually all wireless devices intermittently and randomly; sometimes not affecting a device for weeks at a time and other times affecting it multiple times within an hour
  • I have tried disabling 'Fast Transition' and 'U-APSD', both of which I have observed to cause problems in some environments, but no change was observed
  • Yes, I've tried turning it off and on again :)


So, I'm stumped.

Any suggestions / ideas / input would be greatly appreciated!



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  • 0

    I can't remember a similar issue here, Sam - what does Sophos Support say?

    Cheers - Bob

     
    Sophos UTM Community Moderator
    Sophos Certified Architect - UTM
    Sophos Certified Engineer - XG
    Gold Solution Partner since 2005
    MediaSoft, Inc. USA
  • 0 in reply to BAlfson

    Waiting on their analysis at the moment; I'll update this thread once we get to the bottom of it!

  • 0 in reply to SamFickling

    Hey Sam, do you have any news? We have exactly the same problem? 

  • 0 in reply to Fabian Payerl

    Hi Fabian, I'm still working through the issue with Sophos support.  They asked me for additional logs etc when the issue occurred again which I have now provided.  To be honest I don't think the logs will help, but we have to go through the standard process I guess.

    I suspect that this one will take a while to get to the bottom of.

    Interesting that you are having the same issue though!  Tell me about your situation.

  • 0 in reply to SamFickling

    Sam

    Did you try to assign the APs their own static channels?  Make sure they are not using the same channel because that will actually cut down your speed and signal.  I would analyze any traffic using a free tool to see what other APs are around you which may be interfering with yours, and assign the channels that any possible ones aren't broadcasting on.

    OPNSense 64-bit | Intel Xeon 4-core v3 1225 3.20Ghz
    16GB Memory | 500GB SSD HDD | ATT Fiber 1GB
    (Former Sophos UTM Veteran, Former XG Rookie)

  • 0 in reply to Amodin

      No, I did not do this for a few reasons:

    - Assigning static channels may cause more problems than it solves.

    - Since these are fully integrated Sophos APs, they should be able to effectively manage their own channels and in fact auto channel management is the optimal configuration for the constantly changing wireless environment.

    - The issue is not one of signal strength or interference.  It is very much an on/off issue.

  • 0

    By way of an 'update'; Sophos gave me a command to run on my firewall to improve the AP handover process:

    1. Enable the "Fast roaming"
2. Set the bridge kick out to 1 using the command: cc set awe global bridge_update_kickout 1

The bridge_update_kickout is a feature of the Access point, when a client roams to target AP from source AP, the source AP assumes that the client is still on the source AP and thus it does not forward the ARP response packets.

    Unfortunately this has not resolved the issue.

    I will continue working with Sophos and add to this thread with any updates as they happen.

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