Seeing packet loss as soon as I use Xfinity's network - any ideas?

Upgraded from 100 down to 300 down hoping that it would make WFH better for all of us in the house. I did not. I implemented QoS on the router, that helped tremendously, but I was still getting issues streaming, video calls, during gaming (felt like packet loss) - so I started to investigate.

Equipment:

1. Modem - Arris SB6183 (3.0)
2. Router - ASUS RC68U (Merlin firmware)
3. DNS resvolver - local, hardwired
4. Comptuers wired w/ Gigabit where testing is involved

   As you can see in the graph below - I am getting packet loss to the _very first Xfinity IP_ that I encounter as soon as I leave my own network. That tells me there's an issue on Xfinity's side, as there's no packet loss between my computers on the LAN.

    

   What can I do to resolve this?

    

   Things I've tried:

   1. Power cycled our WiFi router
   2. Power cycled our modem
   3. Called Xfinity, have them "re-provision the modem" - twice.
   4. Disabled QoS on the router (no difference in packet loss)

       

https://imgur.com/a/ZkaCSoy

xfinity packet loss