Hello, welcome to the forum.
Yes, the Aqara Hub M3 is necessary for most of your scenarios. It acts as the “brain” of the system:
Local work: The main advantage of the M3 is the ability to perform automations locally (“Edge computing”), that is, they will work even without the Internet.
Device support: Your Zigbee switches, sensors and curtains need a hub to communicate with each other and with the application.
Not directly. The Aqara Hub M3 only supports the connection of Zigbee devices from Aqara.
However, you can integrate third-party devices via the Matter protocol. For example, if you have other brand bulbs that support Matter, you can add them to the Aqara Home app via the M3.
If you have a global hub M3, you must use the Aqara Home app with the “Others” region or your country. Chinese sensors purchased on AliExpress usually do not allow you to add to the global hub in the official app.
If you plan to use Apple Home, Aqara regional restrictions do not apply there - the devices will see each other. But for the initial setup in the Aqara app, it is better to buy devices from the same region.
Yes, it is possible. For this you can use a smart relay T2 (T1), which is connected to the contacts on the control board of your gate.
You can set up automation in Apple Home or through shortcuts. There is also the option to do this when your iPhone enters a radius of 100 meters from your home, the gate opens automatically.
This is not possible directly. Xiaomi Smart Home Hub 2 works in the Mi Home ecosystem, and Aqara Hub M3 works in Aqara Home.
You will not be able to add the Xiaomi curtain motor directly to the Aqara hub.
Solution: Combine both hubs in Apple Home. There you can create one “I’m home” button that will simultaneously open the curtains (via Xiaomi) and turn on the lights (via Aqara).
Yes. To control your home via Apple Home when you are away from home, you need a Home Hub.
For a two-story house, one M3 hub may not be enough for stable coverage due to the overlap.
Zigbee Mesh: You don’t have to buy a second hub. Aqara smart switches with a neutral work as Zigbee signal repeaters. If you have smart switches on both floors, they will create a stable network (Mesh) that will “bounce” the signal from the hub to the most distant sensor.
The hub is best placed centrally on the first floor.
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MY personal advice: Since you are a beginner, start with the global version of the Aqara Hub M3 and buy official local accessories. This will save you from regional settings issues and ensure Matter support in the future.
Once again, I wish you a pleasant journey in the Aqara smart home!