For half the price you could buy a Raspberry Pi that just runs a simple watchdog program doing the internet connectivity check. Upon a problem, it could connect to your modem's web admin page and launch a restart from there.
See my other post where I am using my Pi and reset my Wemo... Initially I was going the route to reboot the modem through the web interface until I noticed my stupid modem doesn't offer such option in the web interface! Since I had a spare Wemo Plug I was not using for a while I used that instead.
