Aqara Smart Lock U400: UWB, Home Key, Matter over Thread and Compatibility Notes

Aqara Smart Lock U400 is a 2026 Aqara deadbolt notable for combining UWB, Apple Home Key and Matter over Thread. For consultation, these should be treated as three separate layers: UWB is used for position/direction-aware proximity, Home Key is a digital key in Apple Wallet, and Matter over Thread is the smart-home connectivity layer.

UWB Unlock on Approach differs from ordinary Bluetooth proximity

According to Aqara information recorded in the source article, U400 uses UWB distance and approach-angle measurements to determine whether an authorized user is genuinely approaching the door. The objective is to reduce unintended unlocking when the user is inside the home or merely passing near the door.

Which Apple devices support Unlock on Approach?

The source article records Aqara's 2026 compatibility guidance: iPhone 11 or later except iPhone SE 2nd/3rd generation and iPhone 16e, running iOS 18.5 or later; Apple Watch Series 6 or later except Apple Watch SE, running watchOS 11.5 or later. Compatibility can change with firmware and operating-system updates, so it should be checked again before project handover.

Home Key and Unlock on Approach are not the same feature

Home Key stores a digital key in Apple Wallet and enables tap-to-unlock with a compatible iPhone or Apple Watch. Unlock on Approach uses UWB for hands-free unlocking when a compatible device determines the correct approach direction. A lock supporting Home Key does not automatically support UWB hands-free unlocking.

Matter over Thread: Aqara Hub is not mandatory, but the correct infrastructure is

U400 uses Matter over Thread. To use it in a specific Matter ecosystem, the source article states that a compatible Matter Controller and Thread Border Router are required. For Apple Home, it references Thread-capable Home Hubs such as HomePod mini, HomePod 2nd generation or suitable Apple TV 4K models, subject to Apple's current requirements.

Backup unlocking methods

• UWB Unlock on Approach on compatible devices.
• Apple Home Key and compatible digital keys.
• Fingerprint: up to 50 fingerprints according to Aqara information recorded in the source article.
• Permanent, scheduled and offline PIN options depending on supported configuration.
• Aqara NFC card.
• App/voice control through a suitable ecosystem.
• Mechanical key.
• USB-C emergency power when batteries are depleted.

Battery, auto-lock and outdoor durability

The source article records an Aqara claim of battery life up to approximately six months depending on use, low-battery alerts and USB-C charging/emergency power. U400 also uses a gyro sensor to support Auto-Lock on Close, the exterior side is listed as IP65, and the product is described as BHMA-certified for residential applications.

Aliro and Samsung Wallet: verify firmware and region

The source article notes that Aqara positions U400 as Aliro-ready and has announced expanded digital-key support including Samsung Wallet on compatible devices. These features depend on ecosystem, firmware, region and end-user device, so they should not be treated as default capabilities for every project.

Installation in Vietnam: mechanical compatibility must be surveyed

U400 is designed around the single-cylinder deadbolt format common in North America and selected markets. For aluminum doors, mortise locks, steel doors or multipoint-lock doors commonly found in Vietnam, measure door thickness, backset, bore holes, frame clearance, opening direction and strike-plate construction before quoting. Do not select U400 based only on app features.

Handover checklist

• Check the exact iPhone/Apple Watch model and OS version.
• Confirm that the Matter Controller and Thread Border Router are operating reliably.
• Test Home Key tap-to-unlock and UWB Unlock on Approach separately.
• Test fingerprint, PIN, mechanical key and emergency power.
• Verify Auto-Lock on Close after strike-plate alignment.
• Record SKU/region and firmware in the handover documentation.

Verification sources recorded in the Vietnamese article