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 (every 60 feet for Z wave plus).
.3) zigbee repeats only for zigbee and zwave repeats only for Z wave. The repeaters form the “backbone” of the network. So there will be one backbone for zigbee and one backbone for zwave. When installing several devices at once, install the repeaters first, beginning closest to the hub and working outward, so that the other devices will be able to use them to reach the hub. Then go back and install the battery powered devices. Using this method, zwave plus Devices should be able to be paired in place.
Some Z wave classic devices may need to be moved close to the hub to pair, and then moved to their desired location (or you can move the hub close to the device). Z wave locks will need to be paired very close to the hub so that they can exchange an encryption key.
If you do have to change the location of any devices, including moving the hub around, during the join process, you will then need to run a Z wave repair utility once everything is in place to update the neighbor tables.
.4) battery powered devices do not usually repeat, but most mains-powered devices do including most plug-in modules, light switches, in wall relays, and plug in sensors. It is up to the manufacturer though, so check to be sure. Sengled, for example, has made the decision that none of their smart bulbs will repeat.
.5) Z wave plus has the longest range per device of the Z wave/Zigbee options
.6) The hue bridge forms its own mini network and none of the devices connected to it will repeat for any of your other devices
.7) wi-Fi is irrelevant to the performance of zigbee/Z wave devices except that very strong Wi-Fi can drown out nearby Zigbee. For this reason, locate your SmartThings hub at least 3 m from your Wi-Fi router and any Wi-Fi access point.
.8) Different architectural features can make it harder or easier for signal to get through, effectively making the range shorter. For example, foil backed insulation inside a wall might make it hard to get signal through to the next room. Signal might pass easily from one side to the other when a garage is empty, but be blocked by cars when the garage is full. These kinds of obstacles may require an additional repeater or changing the placement of devices.
.9) Z wave is limited to four total hops per message between the end device and the hub, zigbee allows for 15.
A zwave network is limited to 232 Devices, including the hub. A zigbee network can support many more. so you will theoretically be able to add up to 231 Zwave devices to your SmartThings account at one location, although you may start to encounter some issues if you go over 40, it just varies.
However, as of this writing the smartthings hub can only handle 64 non-repeating zigbee devices connected directly to it. These are most commonly battery operated sensors or the Sengled brand lightbulbs. If you try to connect more than 64 non-repeating zigbee devices directly to the hub, some of them will just drop off the network.
The good news is that every time you add an additional zigbee repeater, it can “parent” some of the non-repeating devices, leaving more slots for the hub again. The number that each new repeater could take varies by brand/model, but is typically 3 to 7.
Also, your SmartThings account has a limit on the total number of devices you can add per location, independent of protocol. (As of August 2021, this was 200.)
.10) each end Device keeps a list of its closest neighbors. Anytime you add a new device to the network or physically relocate a device, you should run the Z wave repair utility for Z wave devices or do a zigbee heal for zigbee devices to make sure that all the neighbor tables are up-to-date.
To do a zigbee heal, take the hub off power (including removing the batteries) and leave it off for at least 20 minutes. When you put the hub back on power, all the individuals zigbee devices will automatically update their neighbor tables.
To do a Z wave repair, follow these instructions:
This process can take a while for both Z wave and zigbee, so you may not see efficiency improvements until the next day.
Also, the route that you see in the smartthings IDE (the web interface to your smartthings account information) is not the only route that device can use: it’s just the one that was used most recently at the time the report was made. And the report does not update in real time. So in general you don’t need to worry about that route even if it looks strange. The automated routing algorithms take into account a lot of information that we as humans don’t have like network traffic and signal strength. But the route information can be helpful in identifying a bad repeater or not enough repeaters. In particular look at the ratio of failed message transmissions to total message transmissions. If there are a lot of failures, you probably need another repeater.
People would then know 95% of what they need to know to set up an efficient mesh network. One line in the hub user manual “go online for information on how to set up the most efficient communication network for your home automation devices” and a one page web explantation of those ten points and you’d save a lot of support calls.
Professionally installed systems, even Xfinity home, obviously don’t have to do that. Their installers will deal with those issues.
But I do think it makes sense to provide the backbone planning information for a DIY system.
JMO 
