Whether it's a range or general connectivity issue, here's what to try.
Network Repair is a feature that refreshes the connections between the hub and devices, and allows the hub to find the best communicate route to each device. You can repair the network using either the SmartThings Classic app or the newer SmartThings app. See the steps below depending on which app you're using:
For new SmartThings app users:
For Classic app users:
We'd recommend starting by disabling the Health Check in your app and performing Network Repair.
Here is how to disable Health Check:
And here's how to perform Network Repair:
Before sending any commands to your Motion Sensor, wait until you see the "Z-Wave Network Repair finished" message - this can take up to 15 minutes. Once repair is completed, try including the sensor back into your network.
If Network Repair doesn't help, try bringing the sensor closer to SmartThings. Exclude and re-include it from within 3 feet of SmartThings. If the sensor includes successfully and stays connected, it's possible the previous spot is out of the hub's range or there are too many interferences in that location.
We'd also recommend excluding and re-including the sensor from the installation location directly. Similar to the idea behind Network Repair, it's possible that SmartThings hasn't found the most efficient route to your Motion Sensor. This can occasionally happen when you include a device near the hub and then move it away to be installed.
If you've tried all of the above and are still seeing the same issue, please don't hesitate to reach out! Our team will be happy to help.