Set up alert when or be loses connection to the Internet

[KH2]

Does anyone know of a way to receive an alert when your Internet connection goes down?

[schumaku]

What do you have in mind - a siren or a flashing/rotating amber light on the router?

[KH2]

Alert to my cell phone.

[schumaku]

And how does the router reach your cellphone - once the Internet is down?

You might look for some services allowing to monitor some connectivity, or service reachability, to get notified once the router or a service hosted in it or behind on the LAN is no longer reachable.