Issues With Speed and Packet Loss

Let me preface this by saying that an Xfinity tech came out to my address, checked my equipment, and verified it was fine. He identified an issue with signal from the circuit, replaced the coaxial connectors, and it was fine. For a week.

I've been having speed issues for the last month, on and off. Instead of gigabit speeds, it will frequently drop to 50 mb/s or less (with a bare minimum of 5% packet loss).

The Xfinity automated troubleshooter finds no issue with my service because my modem is connected, and tells me to kick rocks. If I schedule a callback, the Helpdesk Agent runs through the generic troubleshooting steps, finds no issue, and tells me to kick rocks and talk to my modem manufacturer. The last one I spoke to actually told me to reset my mobile phone to resolve the issue, and then hung up on me when I told them that was ridiculous and I would not be doing that (if you can believe it).

I've factory reset my MB8600 and re-set it up, which made no difference. The same with my Asus RT-AX68U.

After running a tracert and noticing drops and latency outside my home network, I decided to check my Modem's log and connection status. I'm seeing a large amount of MDD Message timeout warnings which line up with the packet loss I see, and a massive number of uncorrected code words on all Downstream channels. I've attached the logs and the connection info below.

To my eye, it looks like an issue upstream on the circuit, but I wanted other eyes on it and maybe to speak to someone at Xfinity that isn't reading a script and refusing to deviate from it. Any help would be appreciated.