Intermittent Connection Drops

I see a few other people have this issue. I have had issues for over a year. I called comcast many times and eventually comcast had a tech come out to check a few things. He got rid of a splitter I had and told me that was my issue. I stil had issues. Comcast told me since I own my own modem there is only so much they can do since they see a signal going to my modem. I went out and bought a brand new modem and router (Netgear CM110 and a Netgear Nighthawk AX6).  I continued to have issues. Comcast sent over another tech since the odds of my old modem and the brand new one were both at fault. The tech said the connection issues are from noise in the line and nothing can be done. I went away for a  couple month and when I came back the issue is worse than before. I called Comcast and they "ran some tests" and said the signal looks healthy and that I should call the Manufacterer. I called Netgear support and asked me to check the Upstream? Downstream channels. One of my 32 Downstream channels is unlocked. The support guys said that could be my issue right there and my powerlevels on the Downsteam were too high. They said it can only be locked and power levels lowered by the ISP. I called comcast and the lady I spoke to had no idea what I was talking about. I then spoke to a supervisor who told me those things are not controlled by comcast...... Does anyone know which side is lying/cluless?