If you want to receive notice that something is down you need to look first at how the Dude looks at the status of a device.
Here is the order of things
1st: Up -> 2nd: unstable -> 3rd: down
So if you want notification when it's unstable put a check next to: up -> unstable
if you want notification when it's down you would put a check next to: unstable -> down
and for when it's back up from down you would put your check next to: down -> up
or for when it back up from unstable put your check next to: unstable -> up
I only look for Status of Down and then back up.
So I only have checks next to
unstable -> down
down -> up