You might want to take a look at the FAQ section of the forum. I think you’ll find a lot of your questions are answered there.
FAQ
General FAQs for Devices and SmartApps
In particular, the following two FAQs should help. (These are clickable links)
Start with post 11 in the following thread, then go up to the top and read the whole FAQ:
One more thought. While I understand the marketing reasons for the decision, the fact that SmartThings gives customers zero guidance on how to set up a network backbone does lead to a lot of frustration that shouldn’t have to exist. if people knew that .1) The hub should be located centrally in the home, both vertically and horizontally. Don’t put it in a garage or basement as those have concrete and pipes and metal objects which will reduce signal. If your Internet router is off in some inaccessible corner, you can use a Wi-Fi access point that has a ethernet port on the side and plug into that. Also, the hub should not be put in a cabinet. You just want to make it as easy as possible for signal to spread around your house. .2) you need one device that can repeat about every 40 feet…
And specifically on lightbulbs as repeaters:
Hue Bridge Lightbulbs connected to a hue bridge are repeaters–but only for other devices attached to the same bridge. They essentially form their own mini network. So they won’t help with nearby sensors. Zwave bulbs Zwave lightbulbs like those from Linear and aeotec typically are repeaters – – but only for Z wave. These can actually be very useful in some specific use cases like getting zwave signal down basement stairs or across a garage.![]()
zigbee bulbs connected directly to the ST hub Zigbee lightbulbs like hue or Osram if connected directly to the SmartThings hub without using a bridge shift from the ZLL profile to the ZHA profile and then do typically act as repeaters for other ZHA devices. Or if they are Zigbee 3.0 devices, they will connect to the smartthing…