Upload rate randomly plummets to 0.20 mbps - 0.5 mbps

My upload rate plummets to almost 0 (0.2 - 0.5) at random times of the day. It will last about 10 seconds to a minute. This issue might not be recognizable to most Users, but I am constantly using my upload for my job and it has been affecting me for the past 2 to 3 months. In the past week and a half, I have had 3 techs come out. 1 Tech changed the aerial line going to my place, 2nd one came out and said he couldn'd do anything because the line has already been changed, and the 3rd replaced my coax cable going from my house to the connection outside. I have had 2 differen routers from Cox that had the same issue. I finally went out and bought my own and got the NetGear c7000. I have the Premier Tier so this router easily matchees the specifications for this tier. A technician will not see the upload spikes in my internet unless he/she sits there until it happens. A 30 second look at my levels will not show the spike unless it happens to occur at during that short window of time. I believe I am experiencing ingress and t3 timeouts, but cannot be sure. My coax was replaced yesterday and everything seemed smooth until I ran a test this morning for 3 hours and left for work. I came home for lunch and noticed another drop to 0.20 mbps after the test was running for about 10 minutes. Running tests using the cox speed tool or any other 1 time tests will not help due to it only measuring for that period in time. I am not having issues of getting the speeds I pay for, but this drop to nearly 0 upload at random times is really affecting my job. I will return home after work at 4pm and will see how the test ran, but already seeing that drop to 0 this morning essentially means Im still receiving the same issue. 

I appreciate any help

Update: checked after work yesterday and the issue is still occurring. Tested on several PCs over night and it was occurring on those machines as well. Haven't had reliability after 3 Tech visits and 2 months.