What happens around 3:30am EST lately?

Hi there,

   I've had the same setup for the past 2-years now, and everything has been solid.

   That past two weeks however, every morning between 3:30am and 3:45am EST, I lose full connectivity for 1-2 minutes. I know this, because I have a heartbeat setup with multiple online services, and for the past two weeks my modem constantly loses connection in this timeframe.

   Is this maintenance being done? This never happened prior to two-weeks ago. Everything works fine outside of this window as well.