This is the best way to do it, you should never have changed to Static IP, no one advised you to do that. When you reserve the IP on the router you always want the device (hub in this case) set to DHCP.
If all the devices stop working again first thing to try is this:
Shut down the hub from the menu if you can get into the UI.
Unplug the hub for 30 seconds, then plug back in.
Wait for it boot and see if its working again.
This can happen sometimes, but should not happen often.
Oh Also, on the zwave details page, if you have an "Update Firmware" button at the very top, run that update, this will also help the zwave work better.
Here is directions, and there was one other update after this as well to get it to 7.18: C7 2.3.1 and Z-Wave Firmware 7.17.1
