After a long day of installing devices (I checked them every time I installed them), suddenly my C-7 says that most zwave devices either are not responding or have failed. I tried several zwave repairs, I rebooted the hub, I shut downs the hub and restarted it but that's where I am. I can no longer add a zwave device. I am not sure where to go from here, so if anyone has an idea I'd be glad to hear from you,.
You should give it time. You don't want to do a lot of adding at once. The repeating devices on the mesh will be very busy rebuilding neighbor tables. Once things settle, they should begin to respond again.
Make sure you have enough mains powered repeaters too. Otherwise your mesh will be weak and you'll have reoccurring issues such as slow and unresponsive devices.