Hardware: nRF54LM20 DK + nRF7002 EB II shield SDK: NCS v3.3.4 Sample: Unmodified Matter light bulb sample
(nrf/samples/matter/light_bulb) Build command: west build -p -b nrf54lm20dk/nrf54lm20a/cpuapp -- -DSHIELD=nrf7002eb2 -DSB_CONFIG_WIFI_NRF70=y -DCONFIG_CHIP_WIFI=y Router: Eero (Apple-recommended, mDNS/Bonjour supported) Controller: Apple Home with HomePod Mini as home hub
Problem: After commissioning the unmodified Matter light bulb sample to Apple Home, the device works for a few commands (on/off, level control all succeed), then becomes unresponsive. Apple Home shows "No Response." The device does not recover unless reset.
Observed behavior:
- Commissioning succeeds (PASE → WiFi → CASE all complete)
- Light control works for 5-10 commands
- Device starts failing retransmissions (max retries: 4 → failure)
- Sessions go defunct, subscriptions torn down
- Apple Home shows "No Response" permanently
Relevant log errors:
E: [IN]IPV6_PKTINFO failed: 109(on every mDNS advertisement)E: [DIS]Failed to advertise records: 46(intermittent)E: [EM]<<5 Msg Retransmission failure (max retries:4)(device sends but HomePod doesn't receive)[SC]SecureSession State change 'kActive' --> 'kDefunct'
Analysis: The device sends UDP responses but they don't reach the controller. This appears to be WiFi-layer packet loss rather than a Matter stack issue. The retransmissions show the device is trying to respond but packets are being dropped.
I noticed commit ba4fc5cc1f in sdk-connectedhomeip reverted the MLDv2 join fix ("Enable MLDv2 join procedure for IPv6 Multicasts"). Related known issue: KRKNWK-19524.
Questions:
- Is there a patch or workaround for the UDP packet loss on nRF7002 with Matter over WiFi?
- Does NCS v3.4.0 resolve this?
- Is the MLD fix being re-introduced in a future release?
Note: I'm aware the nRF7002 EB II dev guide states WiFi is "experimental" and "not optimized for performance" on this platform. However, the unmodified Nordic Matter light bulb sample is advertised as supporting this exact hardware combination (nrf54lm20dk/nrf54lm20a/cpuapp with nrf7002eb2 shield) in the official documentation. If this combination isn't stable enough for Matter over WiFi, the documentation should reflect that.
