System/Script to check when your NAS devices go offline/fail ?"
Can anybody help me with this?
I’ve got no idea what the proper word is, for this… 
/Tools/netwatch
When the ip of your NAS wont answer the script linked in Down will activate. When it’s coming back up, the script in Up will be triggered.
In you up and down script you can choose to do whatever action you want (send email, reroute to another nas, etc…)