Internet disconnects intermittently

I'ved moved into my condo months 6 ago now, and for about 3 months, my internet disconnects intermittently throughout the day (sometimes 3-4 times), then comes back on. I originally had an Arris surfboard and saw all the lights reset when the disconnect occurs. Thinking it was a modem issue, I went out and replaced it with a Nethgear nighthawk and still have the same problem. I tried plugging the modem in both outlets in the home and still to no avail. 

I called comcast, the rep walked me thru the basics (made sure my wires were plugged in, sent signals to the modem, etc) but it really has nothing to do with my modem/wiring. I really think its comcast service or wire from the exterior. I originally had a tech scheduled but the same day I made the appointment, I recieved a strange call from Comcast "advanced support" telling me they found that the signal going into my home was up to their specifications and that they had fixed it which should resolve the issues, the asked that I cancel the appointment which I did. A week later, my internet drops and Im running out of patience. I work at home and I disconnect from meetings when I preset! I now have to call Comcast back to rescedule an appointment which Im really annoyed about, I just need the internet to work as expected!