Upstream packet loss in Cranston, RI

I'm a Cox Business customer for my home office, and have been seeing about 1% to 2% upstream packet loss on a regular basis, off and on for the past few months.  This causes very slow uploads (under 5 megabits) due to all the TCP re-transmissions.  The results are the same, both on wired or wifi. Based on my observations, it seems to get worse during peak times and better on off hours. For example, this Sunday night after 11 PM, there was no packet loss and I was getting a full 300 megabits down, 30 megabits up.

I've been running a variety of tests. These are typical results from PacketLossTest.com:

https://imgur.com/a/xwVyY2j

Here's Ping Plotter over the past couple days:

https://imgur.com/a/9cEbHd2

My modem is an Arris SB8200. Here are some stats:

https://imgur.com/eyvhoym

https://imgur.com/2ox8nHm

What's the best way to get this resolved?