Inconsistent/Extremely Low Upload Speeds

I have the COX Ultimate internet package (300 down and 30 up). I decided to start streaming this summer which made me realize that I have extremely inconsistent and mostly low upload speeds. My download speeds are more then adequate ranging from 200-350 MBps. My upload speeds however tend to hover around 2 Mbps. At various times in the day it might get closer to the advertised speeds but inevitably will plummet back down. More often than not the speeds are too low to stream which is extremely frustrating. 

I am using a Netgear AC1900 Model C7000v2 for a modem/router. The connection is wired straight from the modem to the computer. The computer is brand new with all updated drivers. There are no spliiters and coaxial cable runs from the wall straight to the modem. I've tried just about everything I can think of but my knowledge is not that expansive.

Furthermore I did have a technician come out. He rewired the line to the house from the street due to the presence of damage. So to my knowledge all of the line involved is brand new. However, the problem persisted afterwards.

I've tried calling multiple times but all the help I receive tends to be generic restart the modem suggestions.

Any help would be greatly appreciated.

Tanner H.