A good place to start is refreshing your mesh network's connections. You can do this by first disabling the Health Check in your SmartThings Classic app and performing Network Repair. Here is how to disable Health Check:
1. Tap Menu (Android) / More (iOS)
2. Tap Device Health
3. Toggle the Device Health switch to the OFF state
4. Tap Done
And here's how to perform Network Repair:
1.Click on the Menu icon in your SmartThings hub.
2. Tap Hub is Online
3. Tap Z-Wave Utilities
4. Tap Repair Z-Wave Network
5. Tap Start Network Repair
Before sending any commands to your Power Strip, 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 device back into your network.
If Network Repair doesn't help, try excluding and re-including the Power Strip. It's possible that the communication route between SmartThings and the strip wasn't established correctly the first time. Exclusion might help the hub find the best route to the device.
Next, try installing the Power Strip closer to your hub. This is a good way to see if the issue really is range or if there's a better spot for your strip. Once you've moved the device, remember to exclude and re-include it to give them a chance to connect properly.
If you've tried all of the above and are still seeing the same issue, please don't hesitate to reach out!