This is a very common issue that folks will face when using Z-Wave devices. Over time you’ll see that your device connectivity gets slower, commands take longer to execute (higher latency), sometimes they don’t execute (loss of packets).
This happens due to a variety of reasons and this Wiki will provide you with some tools to fix these issues. While this isn’t a magic bullet to fix all Z-Wave problems, it should resolve the majority of common issues with a Z-Wave Mesh.
Ghost devices: Ghost devices are devices that are no longer connected to the mesh but they still show up in the routing tables of the hub (controller). These can cause significant havoc in the mesh including slowdowns, high latency, random unresponsiveness and even loss of packets in the worst case scenario. This article talks about how to identify and get rid of ghost devices: FAQ: How to remove ghost devices from your z-wave and zigbee networks
Buffering devices and repeaters: Lack of buffering devices causes loss of packets in the mesh. This is one of the most common issues especially when using battery powered Beaming devices like Smart Locks, Battery Thermostats, Battery Sirens etc. Typical symptoms include random loss of connectivity, inconsistent operation etc. TLDR; make sure you have atleast a few mains powered Z-Wave Plus devices (like outlets, plugs, thermostats etc) which can act as beaming repeaters to keep the mesh strong and avoid issues related to a weak mesh/signals. This post explains it great length and also provides recommendations on how to fix these issues and which devices act like beaming repeaters: FAQ: why would I need another beaming repeater if my zwave lock is already close to my hub?
Mesh repairs: Over time when you add/delete and move devices around the house, the mesh routing information isn’t always up to date. This can cause a general slow down in the mesh due to in efficient routing. You can a Z-Wave repair using the SmartThings app. Keep in mind this process generates a LOT of traffic between all the devices while they discover and update the routing tables and can often make the mesh very slow/unresponsive while the repair in process. This process can take from 10 minutes to an hour depending on the number of device in the mesh so keep this in mind when timing when to run a repair. Also it’s not recommended to run a repair very often, typically only when there are changes to the mesh (add/deleting devices or moving device locations) should this process be run. Click here to read how to do a Z-Wave repair using the SmartThings mobile app.
Offline repeater devices: If you have a mains powered repeater device which is permanently offline (e.g. no longer used), it can help to remove those devices from your SmartThings setup. While technically after doing a Z-Wave repair it should compensate for devices which are offline and avoid routing through them it can improve the overall mesh quality to delete these devices from your controller/hub using the SmartThings mobile app. It’s best to always exclude devices if possible but as a last resort you can delete them from the SmartThings mobile app (preferred over deleting them from the IDE).
Feel free to share your feedback and I will keep this Wiki updated.