Now it works...

Original: Shows me my Time Capsule and own computer. Doesn’t list 12 other devices that our old Windows PC sees. Pretty worthless.
Now, as of Sep 21, 2015 update: Shows me everything on my network. Doesn’t identify iPhones, but shows their IP address (just doesn’t give any more info)

Sometimes you might need to click Start Scan again just to make sure the list is up to date. Bottom line: It works.

FlyAnotherTrip about My Net - Network Scanner