Hi,
From someone who's had issues having my Apple TV (located in the family room, far from my front door) access and control my August smart lock, I can confirm to you that adding a second Apple TV closer to the lock fixed the problem.
I have an Apple TV in our family room and from day one, it had issues connecting to my smart lock on the house's front door. When I installed a second August smart lock (door to the garage, much closer to the family room) last week, I noticed that there were zero connection issues between that new lock and the Apple TV. I bit the bullet and bought another Apple TV, installed it in the office (very close to the front door lock) and 100% access now. No more problems.
Problem is that the August smart lock (and some other IOT devices, like Elgato) only uses Bluetooth (low energy) for communication and the range of the BTLE signal is very limited compared to Wi-Fi. Even adding the August Connect ''hub'' didn't solve the problem like I had hoped it would, as the Connect will not communicate with the Apple TV over Wi-Fi, even if they are on the same network. BTLE exclusively. :-(
As far as setup is concerned, adding the second Apple TV took all of 10 minutes, with 5 of those being a firmware upgrade. I set it up using an IOS device, so it got the Wi-Fi settings from the IOS device, as well as the iCloud login and everything else. And it automatically started working as a Homekit hub.
I hope this helps.