I am seeing very unreliable Matter-over-Thread commissioning and need help isolating whether the issue is HA Matter, Thread border routing, or device behavior.
Setup
Home Assistant 2026.06.2 on HA Green
Thread radio: ZBT-2, OpenThread RCP 2.7.2.0
Matter Server enabled in HA
Router/firewall: OPNsense
Network: all devices on same LAN, 192.168.20.0/24 (single SSID, no VLAN split for this test)
Devices: IKEA Matter-over-Thread
Phone: Pixel 8, Home Assistant Companion 2026.6.1-full
Core issue
HA Companion commissioning fails every time.
Manual pairing code entry in HA also fails most attempts.
A few pairings succeeded, but success appears random/non-repeatable.
Observed failure pattern
Device enters commissioning mode.
Device appears to join Thread network.
HA then fails at post-join stage with error: cant reach device.
Failure happens with both app flow and most manual code attempts.
What I already tested
Factory reset before each retry
Same LAN/SSID for phone + HA + border router path
No AP/client isolation
VPN/private relay off on phone
Removed failed/partial Matter entries before retry
Retried with multiple IKEA devices
Current state
Some devices eventually paired and work.
Most commissioning attempts still fail.
No deterministic sequence found yet.
Live status at time of failure
Questions
Is this a known issue with IKEA Matter-over-Thread on HA 2026.06.x + ZBT-2?
Are there known Pixel 8 Companion commissioning regressions in this HA Companion version?
Which logs are most useful to differentiate Thread routing failure vs Matter CASE/session failure vs device-side firmware issue?