Packet Loss, Jitter & Latency Issues

I'm experiencing connection drops, jitter and packet loss after a local Xfinity maintenance on 8/24.

Around the same time, I also upgraded to a higher-tier Xfinity internet plan when the modem was replaced, so I'm not sure if that's a contributing factor.

The issue is worse during peak usage hours (around noon and 5-8pm), to the point where the internet becomes unusable.

I've already done basic troubleshooting, including replacing the xFi Gateway modem and all associated cables, and a technician visit as well, to rule out faulty equipment, but the issue persists.