My ISP is cable. Called and said they needed in my house to find the source of the signal that was affecting everyone else in my neighborhood. Literally nothing had changed and my house has been connected since 2010.
The tech arrived and I had them start outside. He replaced every connection/coupling and kept testing. After all of them were replaced, his testing machine showed a perfect signal. Noise eliminated. I was not charged for this service.
I found this baffling. My neighbor’s coax connections affect me?
Uncapped outlets can cause backfeeding, as can damaged cables; when I worked in the field a factory had a damaged coax feed and when one of their machines started up it would knock out the leg. Coax is basically a wireless signal that is stuck on the antenna (wire) rather than a digital signal like Ethernet, and it is a shared medium unlike DSL.