Ongoing erosion of connection quality and stability

Hello. I'm an XFINITY residential internet service customer on the Gigabit plan located in Mendocino County, California. I'm reaching out for assistance with the quality of my internet connection, which has slowly been eroding over the last 2½–3 months, resulting in extreme latency in establishing connections, mounting levels of packet loss and spontaneous loss of connection altogether with increasing frequency.

Having performed a soft refresh through the Comcast XFINITY mobile app and then a factory reset via the device's (a Motorola MB8611) admin page, as well as checking the (straight run, without splitters) coaxial run between the demarc and the modem and tightening/cleaning all connections, I believe I've exhausted the troubleshooting methods available to me. Of note, I've observed in recent weeks that the upstream channels appear to be exceeding the desired power levels, ranging at this moment between 46.8–48.0dBmV without fluctuation. Concurrently, the device's event log shows CM-STATUS messages occurring approximately every 30 seconds that alternate between codes 16 and 24, further leading me to suspect that the issue lies in the physical properties of the drop to my house and not my network cabling or equipment.

Please advise on how best to proceed towards a resolution of these issues. 👍