Highly Intermittent Uploads

For the last around 5 months, I've been dealing with wildly varying upload speeds. At times, down as low as 0.15 Mbps. I've had a tech out, the line signals are good to my modem. The speeds can be good, but at times the uplink (wired connection) drops to the dirt, stopping applications such as games, causing an experience that is very inconsistent, slow and unresponsive. I've called tech support, got ahold of Tier 2 support but they disconnected on me in the middle of my call and they weren't available when I tried to call them back. This issue happens when I am hard wired directly into my router even though I use a separate modem as well. Discord audio is garbled when this happens along with other voip systems. Meetings I've been in have had interruptions or periods of disconnection. 

I've run tracert and pings to various network devices trying to determine where the issue might be but the results so far have been inconclusive. It doesn't appear to be device delays for the ping, but throughput congestion or traffic shaping that is almost cutting off the network and the applications that are using the internet are severely impacted. I am a network Engineer and I am frustrated with the inconsistency of this service. Does anyone have any ideas what might be causing these issues? There are no service impacting reports per the xfinity site but I find your automated tools and customer support lacking. Puyallup WA