Network router join quit join quit every minute

why does the network monitor say joined quit joined quit every minute

You can change the settings to only show new unknown devices that join the network. We changed our default settings to this setting so the alerts would be less frequent and more important.

I guess I really meant to ask why does it join,quit,join,quit so much? Is this common?

What device is joining/quitting? Or is it your Internet connection you’re losing?