I've been using BPTworlds Device Watchdog for a long time, but I just noticed I have a ton of sensors offline that watchdog isn't alerting me to.
My guess is it has something to do with how the last activity at stuff changed some months ago but I didn't notice.
What other similar apps or tools are folks using to get alerted to devices falling off the network?
[EDIT]
Something weird too I just noticed.. A couple of my devices that seem to be offline, I'm seeing zigbee logs for, where they're still reporting rssi.
Example, here's a motion sensor that hasn't posted any events in days. But I'm seeing it active in zigbee logging.