Aqara Smart Lock U400 Review: UWB Apple Home Key Arrives at the Front Door

The Aqara Smart Lock U400 is the rare smart home product that actually does something new. It is the first lock to support Ultra Wideband Apple Home Key, which means the door recognises you as you walk up to it rather than waiting for you to fish out a phone or tap a chip against a reader. Everything else — NFC tap-to-unlock with Apple Wallet Express Mode, a backlit keypad, a physical key, an interior thumb throw — is there as backup, and it's a sensible ladder of fallbacks rather than a gimmick pile.

This is not a weekend retrofit. Unlike August-style locks that clamp over your existing deadbolt, the U400 replaces the whole mechanism, so you're removing hardware and threading a couple of genuinely fragile ribbon wires into the interior unit. One reviewer got two of these fitted on front and back doors in about an hour, which suggests it's manageable but not trivial. Power comes from a removable rechargeable pack that slides out on an orange ribbon and tops up over USB-C, or charges in place through a port on the bottom of the lock.

It's aimed squarely at the Apple household that wants the most frictionless front door available right now and is willing to accept some compromises to get there. Renters and anyone precious about their door furniture should look elsewhere.

The headline feature holds up, which is the main thing. Auto-lock and auto-unlock were reported as reliable over roughly a month of use with no false positives or phantom unlocks — the failure mode people rightly fear most with a hands-free lock. The caveat is that UWB handshaking sometimes wants your phone fairly close before it commits, so the magic isn't always instantaneous. Meanwhile, the full-deadbolt design pays a dividend that retrofit locks can't match: it drives the bolt with enough force to cope with older, slightly out-of-true doors where a piggyback motor would stall against the striker plate. If your house has settled, that alone may decide it.

The design is the obvious weak spot, and reviewers have been blunt about it: chunky, blocky housings on both faces of the door in either black or silver, functional rather than handsome. It's also noticeably larger than Aqara's earlier U100, which can become a real problem if you have a close-fitting security screen door — measure before you buy. The rechargeable pack is a reasonable trade too, but it is a trade: no keeping a pack of AAs in the drawer for emergencies, so charging becomes a chore you have to remember.

One significant gap in our assessment: we have no verified pricing, so we can't judge value, and that's a meaningful omission for a category where premium locks vary widely. On capability alone, though, the U400 earns its recognition as one of the standout smart home devices of CES 2026. It's a first-of-its-kind product that mostly behaves like a mature one — held back by looks and install effort rather than execution.