After BLE setup, Matter uses CASE — certificate sessions between hub and device. Failures show as cannot verify, security errors, or devices that pair then go offline immediately.
Common causes
Hub clock wrong (NTP). Leftover fabric from prior owner. Hub firmware too old for accessory cert chain. Refurb or grey-market hardware with invalid certificates. Beta OS on hub with CASE regressions.
Recovery
Enable automatic date/time on hub and phone. Remove device from all Matter apps; OEM factory reset; recommission on one fabric. Update Apple TV, HomePod, Nest, or SmartThings hub before accessory firmware.
If CASE fails on multiple hubs with a new retail box, contact manufacturer — likely hardware attestation issue, not Wi-Fi.
Verify
Device online 24 hours; local toggle with phone on Wi-Fi only (no cellular).