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If you need a hub to remotely stay connected with all your Apple HomeKit devices, Apple gives you the option of using the Apple TV like the Apple TV (2015) or an iPad that is always powered on and connected on your home network. The Apple TV hasn't enjoyed the same level of success as other Apple's products but it now has the chance to play a key role in Apple's aggressive push to grow its HomeKit ecosystem.
However, setting up your Apple TV as the HomeKit hub means that you need to adhere to using iCloud (including iCloud keychain), and use Apple's Two-Factor Authentication scheme. This makes sense given that Smart Home IoT is based on collecting data from your home and aggregating that data into the cloud so that you can monitor and perform remote and automated actions from the cloud. Given the increased chanced of being hacked when using cloud services, it also makes sense that Apple requires Two-Factor Authentication.
However, if you are not comfortable having an iCloud account and don't like the hassle of Two-Factor Authentication, using the Apple TV as your hub may not be for you. Also, you need to have multiple Apple devices like iPhones, iPads, and Mac's linked to your same Apple account in order for Two-Factor Authentication to be used - this assumes the user is already heavily invested with Apple products which may or may not be true.
After setting up iCloud and Two-Factor Authentication scheme, we had to restart the Apple TV (2015) a few times before we could finally see HomeKit show up in the iCloud screen after we had signed into iCloud on the Apple TV.
If you see the HomeKit section in the Apple TV's iCloud screen, and the home you set up is connected, you have successfully completed setting up the Apple TV as your HomeKit hub. Given that we weren't using iCloud previously, we had to make sure we had the right devices to support Two-Factor Authentication, and had to restart the Apple TV a few times. The overall setup process was a bit painful and not characteristic of Apple's typical plug it in and it just works approach.
Even after setting up the Apple TV (2015) as our HomeKit hub, we were still puzzled at first how to connect the Apple TV to the Bluetooth based Elgato Eve Room Sensor (2016). In the Apple TV's Bluetooth screen, it wasn't able to find the Elgato Eve Room Sensor (2016) despite performing power resets on the sensor.
We also tried to remove all possible sources of radio interference like Wi-Fi routers near the Apple TV (2015) and placed the Elgato Eve Room Sensor (2016) on top of the Apple TV but still no Bluetooth devices were found. Apparently the Apple TV (2015) does not list out Bluetooth Low Energy devices in its proximity.
Just to see if the Apple TV (2015)'s Bluetooth features were working, we tried the Sony MDR-XB950BT Extra Bass Bluetooth Headphones which could be detected by the Apple TV.
We could also see both the Sony MDR-XB950BT Extra Bass Bluetooth Headphones and Elgato Eve Room Sensor (2016) advertise themselves over Bluetooth on our Huawei P9.
There was no Apple Home App or Elgato Home App available on the Apple TV (2015) so you couldn't tell if the Apple TV (2015) was actually connected to the Elgato Eve Room Sensor (2016). However, we then experimented by taking the iPhone 6 Plus together with the Elgato Eve Room Sensor (2016) around the house and outside. We found that even when we turned off Bluetooth from the Apple iPad Pro which had been used to initially connect to the Elgato Eve Room Sensor (2016), the iPhone 6 Plus immediately took over behind the scenes in establishing connectivity to the sensor using Bluetooth Low Energy. We could even use Siri to the temperature being measured by the Elgato Eve Room Sensor (2016).
Once we turned off Bluetooth from the iPhone 6 Plus, we lost connection to the Elgato Eve Room Sensor (2016).
With no Bluetooth enabled iPhones or iPads connected to the Elgato Eve Room Sensor (2016), we then walked closer to the Apple TV (2015) and at about 33 feet line of sight with the Apple TV, we observed the Elgato Eve Room Sensor (2016) achieve connection again and provide data to the Apple Home and Elgato Eve App.
Apple is a master in hiding complexity behind the scenes, allowing different iPhone, iPad, and Apple TV models to connect over Bluetooth Low Energy to the Elgato Eve Room Sensor (2016) without the needing user intervention. However, it's hard for the user to check whether their HomeKit setup using Apple TV is correct and its communicating properly to Bluetooth based HomeKit devices. If Apple TV is going to be the hub for HomeKit going forward, users could really benefit from having a Home App on the Apple TV to be able to monitor and confirm device connections. For now, you can only assume the Apple TV is connected to a Bluetooth based HomeKit device and inquiry about it using Siri.
Apple HomeKit is still in its early days and we are hopeful that the overall HomeKit setup process with the Apple TV (2015) will become easier over time.
