Fire OS 8 loses broadcast/multicast reception after WPA2 Group Key (GTK) rekey

Fire Devices & Appstore Q&A
1

Hello,

I would like to report what appears to be a Wi‑Fi interoperability issue affecting a Fire HD tablet running Fire OS 8.

Device

  • Fire HD 10 (Fire OS 8) 2023 model

Network Environment

  • Linux AP using hostapd
  • Intel AX201 Wi‑Fi adapter (iwlwifi driver)
  • WPA2-PSK (RSN)
  • CCMP/AES only
  • IPv4 UDP broadcast discovery protocol running on the tablet

Problem Description

The tablet receives UDP broadcast packets correctly after connecting to Wi‑Fi.

However, immediately after a WPA Group Temporal Key (GTK) rekey operation, broadcast reception stops.

Unicast traffic continues to work normally.

The tablet remains associated to the AP and existing unicast communications continue functioning.

Only broadcast/multicast reception appears to be affected.

Evidence

On the AP, hostapd logs:

WPA: group key handshake completed (RSN)

Immediately after this event:

  • UDP broadcast packets are no longer delivered to applications on the tablet.
  • Existing TCP and UDP unicast traffic continues working.
  • Wi‑Fi remains connected.
  • Reconnecting Wi‑Fi restores broadcast reception, until the next rekey.

Reproduction

  1. Connect Fire HD 10 to WPA2-PSK Wi‑Fi network.
  2. Verify UDP broadcasts are received.
  3. Configure short GTK rekey interval:

wpa_group_rekey=60

  1. Wait for GTK rekey event.
  2. Observe:
    • hostapd reports successful group key handshake completion
    • broadcast reception on Fire OS stops immediately afterward

Additional Testing Performed

Tested with:

  • WPA/TKIP
  • WPA2/CCMP

The issue occurs with both configurations.

Switching from mixed WPA/WPA2 to WPA2-only does not resolve the issue.

Important Observation

Enabling hostapd:

multicast_to_unicast=1

or

wpa_group_rekey=0

completely avoids the problem.

With multicast-to-unicast conversion enabled, the tablet continues working correctly even across repeated GTK rekey events.

This suggests:

  • Pairwise-key (PTK) unicast traffic remains functional.
  • The issue appears specific to traffic protected using the group key (GTK).

Comparison with Previous Device

A Fire HD 10 (2021) running Fire OS 7 does not exhibit this behavior under the same conditions.

The issue has only been observed on the Fire OS 8 device.

Request

Could this report be forwarded to the Fire OS networking / Wi‑Fi engineering team for investigation?

The behavior appears reproducible and may indicate a problem in GTK rekey handling or multicast/broadcast reception after a successful WPA group key update.

I can provide additional hostapd logs, packet captures, and configuration details if needed.

Thank you.

3

Hi,

Thanks for posting. We have messaged the appropriate team for further investigation and will let you know once we receive an update.

4

Hi,

Thank you for your patience with this issue. Could you share the DSN (Device Serial Number) and any relevant logs so we can investigate further?