Internet Service Is Intermittent During Peak Hours

Around 6/1/2017, my internet service became intermittent.  From around 8:30AM to 3:00PM, several times per hour, Windows shows that I've lost connection to the internet and about a minute later, my Ethernet modem automatically reboots.  Service returns after the reboot for anywhere from ten to thirty minutes, then I lose it again.

A service rep reset the service and this didn't resolve the issue.  The service works fine in the off-peak hours.