Intermittent disconnects, upstream jumping to 55-59 dBmV, only 8Mbps upload on 1000/300 plan

I am posting because this issue still is not resolved. 

This started when I began getting disconnected repeatedly while gaming, and my stream was dropping frames. I logged into the modem and noticed extremely high uncorrectable errors on the OFDM channels - hundreds of millions accumulating in roughly a 24-hour period.

After that, the connection got much worse and the actual signal levels became bad. The modem was only locking onto 1 upstream channel, upstream power was around 59 dBmV, and I basically had little to no usable internet for days.

I had a technician come out. He replaced the barrel connector at the wall, but said the signal was still horrible. He believed something in the building cable room might be causing the issue, but he could not access it because maintenance was unavailable, so the appointment had to be rescheduled.

Today, the same technician came back. During the appointment, the signal happened to look better, so he assumed the problem was fixed. At that time the modem was showing about +10.4 dBmV downstream and around 45 dBmV upstream. However, even with those better numbers, the modem was still accumulating around 200 million uncorrectables per day, and I was still disconnecting while gaming/streaming.

Despite that, he said the signal looked good and left.

Then within about 2 hours of him leaving, the signal became obviously bad again. The upstream power jumped back to around 55 dBmV and has stayed there. I am in a mid-split area and currently only getting around 8 Mbps upload on a speed test.

So now I am back in the same condition as before. What makes this confusing is that the last time the technician saw the line in this state, he admitted the signal was horrible. This time he saw a temporary good window, assumed it was fixed, and left - only for it to fail again almost immediately.

This seems like an intermittent or fluctuating line issue that is being missed whenever someone checks it during a brief stable period. I am in an apartment, so I do not know if this is my unit's line, the building cable room, or something upstream, but it is clearly not resolved.

What is the best way to get Comcast to escalate this and investigate the building wiring / cable room instead of closing it based on a temporary good reading?


This is clearly not normal: