Keep losing internet service, rebooting router fixes it instantly

We've been having problems with losing internet service for about 3-4 months.  It would happen randomly every 10-20 days.  Since rebooting the router would fix the problem instantly, about a month ago we purchased a new router.  Got it all hooked up and everything was fine for about 2 weeks.  When it happened again we decided to purchase a new cable modem (we were upgrading to a docsis 3 at the same time).  Another 2 weeks go by and, again today, we lost all internet service to all computers and devices in the home.  Wired, WiFi, everything.

I was in my den, using the computer (ethernet to the router) and all was fine.  I went out to mow the lawn and when I came back in I went to go to a web page and the browser told me I didn't have an internet connection.

This is getting maddening!  I've called customer service and they have a technician scheduled for a visit tomorrow.  But since reseting the router fixes the problem instantly (every time), I'm sure he's going to blame the router.  This, despite the fact that it's a brand new router.  Plus, the previous router worked perfectly for more than 6 years.

It is NOT the router!

The new cable modem is a Cisco DPC3010.  Does anyone know the URL to see the error codes for this modem?  When I was having the problem before upgrading to the DPC3010, I was able to look at the error codes for the previous Motorola modem and it had a lot of serious errors (which is part of the reason a Cox phone rep convinced me to replace the modem).

Since we have a technician on the way, I'd like to know what kind of error codes might be in the Cisco's firmware.

Thanks!

Mark