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Client driver and firmware defects

When drops follow one client model or firmware version across every access point, the fault usually sits in the client's radio driver or firmware, not in the network.

Ben RutterIndustrial network engineer
  • Updated
  • Reviewed
  • 2 min read
  • 4 sources
On this page5 sections
  1. How it presents
  2. Why it happens
  3. How to confirm it
  4. The fix
  5. Prevent it at design time

Is this your problem? It presents like this

  • One model, or one firmware version of a model, drops while other devices on the same access points and routes do not.
  • The problem started after a client firmware or operating system update, or arrived with a new model.
  • Client-side logs show the client ending the connection itself, or a roam that its own chipset reports as failed.
  • Some drops follow a roam the client reported as successful.
  • Changing the access point, its channel, or its settings does not move the problem.
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Why it happens

The clearest evidence comes from the vehicles’ own logs. Researchers parsed kernel logs from AGVs at an automotive plant over 3.5 months1 and classified 331 disconnections. The largest pattern, 28.91%, was a roam that failed inside the vehicle, which the authors trace to the Wi-Fi chip, firmware, or driver rather than the access point. Those drops averaged 5.1 seconds and reached 24.

A successful roam was no guarantee. 57.53% of the disconnections came after a roam the chipset called a success. In one pattern the host driver could not read the new access point’s beacon from its scan cache. In another, the vehicle deauthenticated itself, and those outages ran longest, averaging 9.3 seconds with a maximum of 30.

Client hardware has always shaped roaming. An early measurement study found that swapping only the client card moved average handoff latency by up to 335.53 ms2 against the same access point. hostapd’s maintainers warn that PTK rekeying is buggy with many drivers/devices.

The AGV study’s authors are careful to say their logs show the direct cause, not the root cause. That is enough to point you at the right device. When the evidence follows one model, stop tuning the network and start testing the client.

How to confirm it

  1. Group drops by client model and firmware version. If one group carries most of the drops, keep going.
  2. Pull the client's own logs for a window either side of each drop. On Linux-based devices that means the kernel log. Note who sent the deauthentication and the reason code.
  3. Check whether each drop followed a roam the client reported as failed, a roam it reported as successful, or no roam at all.
  4. Run the same route with a known-good client and an over-the-air capture. If the network side looks clean, the fault is in the client.
  5. Read the client vendor's release notes for roaming, power save, rekeying, or block acknowledgment fixes.

The fix

  • Roll the affected devices back to the last known-good firmware while the vendor investigates.
  • Send the vendor client-side logs and an over-the-air capture of a failure, not just a description.
  • Apply the vendor's fixed release once it passes your own route test.

Prevent it at design time

  • Treat client firmware like PLC firmware. Test it on a pilot vehicle and route before fleet rollout, with a way back.
  • Pin firmware versions per model and record them in the asset inventory.
  • Make client-side logging with millisecond timestamps a purchasing requirement.

Related causes

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About this page

Built from 4 sources: 1 standards body or lab, 2 research papers and theses and 1 vendor document. Researched and drafted with AI assistance, then reviewed and approved by Ben Rutter on . How pages are made

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Cite this page

Plain

Ben Rutter. "Client driver and firmware defects." OT Wireless, published October 5, 2026. https://otwireless.com/causes/client-driver-firmware-defects/

APA 7

Rutter, B. (2026, October 5). Client driver and firmware defects. OT Wireless. https://otwireless.com/causes/client-driver-firmware-defects/

BibTeX

@misc{rutter2026clientdriverfirmwaredefects,
  author = {Rutter, Ben},
  title = {{Client driver and firmware defects}},
  year = {2026},
  howpublished = {\url{https://otwireless.com/causes/client-driver-firmware-defects/}},
  organization = {OT Wireless},
}