Intermittent upload speeds

I have been reporting issues with intermittent choked upload speeds over the past few months. I have since upgraded to a new DOCSIS 3.1 modem, purchased a new NIC (desktop), cross-referenced the same issue with different network cables to my laptop NIC (old and new modem). Same results. The issue seems to be more prevalent during the evening and weekends. 

A work friend also has the same package, lives in the same region (different node), but has seen no issues. Additionally, when I'm having the issue, we test the same speed checks (Cox site-NOLA, ATL, and Speedtest.net -various endpoints) to the same endpoints, with different uploads. Usually, I'll average right under 10Mbps (sometimes lower), when he has a consistent 20-30Mbps. I completely understand that servers vary with available bandwidth, but the results have been too inconsistent between 2 different Cox modems. This is NOT an equipment issue, but potentially a residential line issue or similar at the tap/node.

Several technicians have come out to my residence, all testing appropriate speeds from each modem at the time. One technician did replace some older configurations at the junction box outside the home, but this has not helped. Another technician scheduled for a line technician to come out, which happened today. Unfortunately, this was a contractor who had another modem to replace and no history of work orders. He was at the house all but 5 minutes and left without saying a word. This contractor also debating with me at my doorstep, saying that I'm only guaranteed 1/10th of the upload speeds. I will be calling in AGAIN to report the same issues this evening, but it's doubtful anyone will do anything other than noting my account I have "internet issues". Very dissatisfied is an understatement.