Intermittent Internet Dropping

I began working from home in June and we use a Xen software.  Unfortunately it has been a nightmare because during my work hours, my internet drops repeatedly for incriments from 5 minutes to 45 minutes during the length of my work shifts.  I have repeatedly unplugged and plugged back in modem and reset it with app.  I have had hours of calls to Comcast, but nothing helps.  I tried seperating 2.4 and 5 lines with different names.  

The dropping only seems to happen when I try to work, and its fine most other times of the day or night.  I am desperate as this is affecting my livelihood.  Please help.