Dear Aqara Users,
Connecting the lock to an app is what users care about most. This guide covers the steps to connect the U400 to Apple Home and Aqara Home — and more importantly, how to troubleshoot and recover when pairing doesn’t go smoothly.
If your situation isn’t covered here, please leave a comment below. We’ll keep supporting you and updating this guide.
Before You Begin: Two Codes, Two Purposes
The U400 has two different codes printed on it. Scanning the wrong one is the most common cause of pairing failure:
Aqara MagicPair Code: Bind the lock to the Aqara Home app (via Bluetooth)
Matter QR Code: Bind the lock to Apple Home or other Matter ecosystems
Important notes:
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Do not scan the Matter QR code when using Aqara Home — the app may read the wrong code, causing the binding to fail or behave abnormally. Pro tip: cover the Matter code with your finger while scanning, so the app reads the correct code.
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The Matter QR code on the lock becomes invalid once the lock is paired with any Matter ecosystem. To add the lock to another Matter platform later, generate a new pairing code from the app it’s already paired to (e.g., in Apple Home: lock settings → “Turn On Pairing Mode”).
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If something goes wrong while pairing with your first Matter ecosystem, first reset the lock, then delete the U400 device card from that Matter ecosystem, and go to your iPhone’s Settings, find the U400 lock that failed to pair, and completely remove its leftover data.
Recommended Setup Order
For the most stable connection and the best experience, follow these steps in order:
- Initialize the lock — start from factory default state.
- Step 1: bind the lock to Apple Home first (scan the Matter code).
- Step 2: bind the lock to Aqara Home via Bluetooth (scan the Aqara MagicPair Code).
- Step 3: finally, connect an Aqara Thread Matter hub (such as Hub M3) for full smart home integration.
Chapter 1: Connecting to Apple Home
Pre-Connection Checklist
Before you begin, verify that your hardware and environment meet the following requirements. If pairing fails or the Home Key fails to generate, come back and check these items first — most failures come from the environment, not the lock itself.
- Apple Home Hub (required)
You need a Thread-enabled Apple Home Hub, updated to the latest software, and already set up and visible in the Home app:
- Apple HomePod (2nd generation)
- Apple HomePod mini
- Apple TV 4K (2nd generation)
- Apple TV 4K (3rd generation, Wi-Fi + Ethernet)
Third-party Matter hubs do not meet this requirement. Without one of the hubs above in your Home, pairing may fail, or the Home Key may not generate properly and won’t sync to your Apple Watch.
- iPhone & Apple Watch
- iPhone 11 or later, excluding iPhone SE (2nd/3rd generation), iPhone 16e, and iPhone 17e, running iOS 18.6 or later.
- Apple Watch Series 6 or later, excluding Apple Watch SE, running watchOS 11.5 or later.
- For the smoothest experience, we strongly recommend updating to iOS 26 and watchOS 26.
- During pairing, keep your Apple Watch sufficiently charged and unlocked.
- Network
- Enable IPv6 on your router — this is required for Matter. Most US broadband plans support IPv6 out of the box, but some routers need it turned on manually. Log into your router’s admin page (commonly 192.168.1.1 or 192.168.0.1, or via your router brand’s app — see your router/ISP documentation), and look for the IPv6 option, usually under Internet / WAN settings.
- Same network: your iPhone and Apple Home Hub must be on the same Wi-Fi (your phone and all hubs on the same LAN).
- If you have a VPN configured on your router, please temporarily disable the VPN while pairing devices.
- Bluetooth: keep your phone’s Bluetooth ON during the entire process.
- Distance
- Keep the lock within 10 meters of your Thread Border Router (HomePod / Apple TV).
- If there are walls in between, stay within 5 meters to ensure signal quality.
Step-by-Step Binding Procedure
If you already have a working Apple Home Hub set up in Apple Home, you can now pair the lock as follows:
- Reset the lock: press and hold the Reset button for 5 seconds.
- Enter pairing mode: press the Set button once to wake the lock and enter pairing mode.
- Add to Apple Home: open the Home app, tap “+” → Add Accessory, and scan the Matter pairing code on the lock.
- After pairing succeeds, a Home Key is automatically created in your Wallet, and Express Mode is turned on automatically.
What is Express Mode? With it on, tap your iPhone/Apple Watch on the keypad to unlock — no need to wake or unlock your device. With it off, you must unlock your device every time you use the Home Key.
If Pairing to Apple Home Fails — Recovery Path
Don’t worry if it doesn’t connect on the first try. Work through these steps in order:
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Step 1 — Re-check the checklist. Go through items 1–4 above (hub model, iOS/watchOS version, IPv6, same Wi-Fi, Bluetooth on, distance). Most pairing failures trace back to one of these.
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Step 2 — Simply retry. Repeat the binding steps once more. Small signal interruptions can sometimes cause a timeout.
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Step 3 — Delete the U400 device card from the Matter ecosystem, then go to your iPhone’s Settings, find the U400 lock that failed to pair, and completely remove its leftover data.
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Step 4 — Reset the lock and pair again. Press and hold the Reset button for 5 seconds, then pair from a clean state.
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Step 5 — The “Deep Reset” method. If it still fails:
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Reset the U400 lock;
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Reset your Apple Home Hub;
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Re-add the hub to your Home in the app;
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Wait until the HomePod status shows “Not Playing” in the Home app (this means it is fully booted and idle);
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Attempt the binding process again.
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Home Key Generated, but Not Syncing to Apple Watch?
Try the following:
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Restart your Apple Watch, or restart both the watch and the iPhone at the same time to trigger the Home Key to re-sync.
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If it still doesn’t sync: create a new Home, reset the lock, and pair it again into the new Home. Keep your Apple Watch unlocked during the pairing process.
Home Key Tap to Unlock Works, but UWB (Hands-Free Unlock) Doesn’t?
Try the following:
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Make sure your phone and Apple Home Hub are both updated to the latest software.
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In the Wallet app, find the Home Key for this home, tap the “i” in the top-right corner to open the details page, and confirm that “Unlock on Approach” appears there and is turned on.
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If you don’t see “Unlock on Approach” in Apple Wallet, restart your phone and Apple Home Hub to trigger a Wallet data refresh.
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If it still doesn’t work: create a new Home, reset the lock, and pair it again into the new Home. Keep your Apple Watch unlocked during the pairing process.
Chapter 2: Connecting to the Aqara Home App
Once your U400 is connected to Apple Home, the next step is to bind it to Aqara Home via Bluetooth to unlock advanced settings (user management, passwords, logs, firmware updates, and more).
Pre-Connection Checklist
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Your phone’s Bluetooth is ON.
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Region check: make sure your Aqara account region is set to a supported location (US, Canada, Singapore, Australia, or New Zealand). Path: Profile > Settings > Region.
Step-by-Step Binding Procedure
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Press the Set button once on the lock to enter pairing mode.
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Open the Aqara Home app, tap “Add Accessory”, and select Smart Lock U400.
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Scan the Aqara MagicPair Code on the lock.
Pro tip: cover the Matter pairing code with your finger while scanning, so the app reads the correct code.
- Follow the on-screen prompts to complete the Bluetooth binding.
If Binding to Aqara Home Fails
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Press the Set button once to re-enter pairing mode, then scan the Aqara MagicPair Code again.
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If it still fails, reset the lock (press and hold the Reset button for 5 seconds) and start over. Note: after a reset, the lock returns to factory state, so you’ll need to rebind Apple Home as well.
Chapter 3: Adding an Aqara Hub (Matter Integration)
Once the U400 is connected to a Thread-enabled Aqara Matter hub, you can use remote control and automations.
Pre-Connection Checklist
Supported hubs (as of June 2026):
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Aqara Hub M3
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Aqara Hub M100
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Aqara Hub M200
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Aqara Hub M300
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Aqara Doorbell Camera Hub G410
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Aqara Camera Hub G5 Pro
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Aqara Camera Hub G350
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Aqara Thermostat Hub W200
Environment requirements:
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Your phone’s Bluetooth is ON; your phone and the hub are on the same Wi-Fi network.
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The hub is already added to the Aqara Home app, and its firmware is updated to the latest version.
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Keep the lock within 10 meters of the hub (5 meters if there are walls in between).
Step-by-Step Binding Procedure
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In the Aqara Home app, open the U400 device page and tap the Cloud icon.
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Tap “Connect” and select “Join Aqara Home through sharing”.
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Select “Apple Home”, then tap “Enter Matter Pairing Code”.
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Switch to the Apple Home app: go to the U400 settings and tap “Turn On Pairing Mode” to generate a pairing code.
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Manual entry (important): switch back to the Aqara Home app and manually type in the pairing code generated by Apple Home.
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Press the Set button once on the lock, select your bound Aqara Hub, and follow the final prompts to complete the binding.
If Hub Binding Fails
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Confirm that your phone, Apple Home Hub, and Aqara Hub are all on the same Wi-Fi network.
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Update the hub firmware to the latest version, and move the lock closer to the hub (within 10 m, or 5 m through walls).
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Before completing the final step, make sure you have pressed the Set button on the lock so it is in pairing mode.
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If the generated Matter pairing code has expired, go back to Apple Home and generate a new code, then repeat the steps above.
Chapter 4: Connecting to Other Matter Ecosystems (Alexa, Google Home, etc.)
If the lock is already paired to Apple Home or Aqara Home, we recommend generating a Matter pairing code from Apple Home or Aqara Home, then entering that code in the other app to complete the connection — rather than resetting the lock. Generating the code from Apple Home is the preferred path.
Doesn’t Work? Here’s How to Report It to Us
If none of the above solves your issue, please send us email (Support@aqara.com) with the following information:
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Your phone model and OS version (if a watch is involved, include the Apple Watch model and watchOS version)
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Your hub model (Apple Home Hub and/or Aqara Hub)
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Whether IPv6 is enabled on your router
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Which step failed, and the exact error message shown on screen
We read every comment and will keep updating the guide based on your feedback. Thank you for your support!
Note on pairing codes: currently, you must manually type the Matter pairing code into the Aqara Home app — copy & paste is not supported for this step at this time. We are working on a fix to make this easier in a future update.
