Cable Box Causing Hourly Modem Disconnects

I have been through it all and have have 3 tech visits and numerous phone calls. After my own trial and error it appears the main cable box is causing my Xfi Arris Modem to disconnect and reset every hour.  I took the cable box back and got a different model (without DVR).  Still having the same issue.  I have reset everything and have tried powering on the modem first then cable box.  The connections look tight and fine.  Tech replaced some connectors and tightend everything.  I even plugged the modem into a different power strip. What in the cable box would send a kill signal back to the modem?  Help!!!