Check out above topic and come back and tell us if you see ghosts in your Z-Wave device list.
You'd be shocked how much a few ghosts (or misbehaving devices) can affect a Z-Wave mesh. They can rip it to shreds... Also check battery powered Z-Wave FLIRS devices like thermostats to make sure they have good batteries, one bad thermostat stopped my entire Z-Wave network a couple years ago.
