This splice was degrading the signal for the internet.
Not long ago, I started to have trouble with internet pages here at my home office. In the browser, I'd get a message saying that the page wasn't found. Two or three frustrating refreshes later, I'd have a page that should have been up in a couple of seconds. It was a bit of a hassle for me, and Red was so upset she couldn't get anything done.
So I called Comcast and told them about the problem. They said that the signal to noise ratio for me and my neighbors was yellow, not green, nor red. He had heard of a case where a customer put a nail in the wall and unknowingly touched the cable, and degrading the signal quality. They scheduled a serviceman to investigate. The customer service rep also told me that they had upgraded the speed of the signals about the same time that I started to drop pages.
The day came when the serviceman arrived. He took one look at my modem and said that they were changing those out. There had been reports that they didn't do well with the speed upgrade. I thought, "Ha! They broke my internet by improving it!"
Then the serviceman went out into the yard. A few minutes later he came back with the tiny assembly pictured above. It's a "coaxial cable splice." Years ago, some technician connected two pieces of coax cable with it. I'm sure it was the proper procedure at the time. It's a plastic sleeve with two crimped metal collars at each end. The problem, which can be seen at the bottom of the plastic part, is a slim metal strip that runs the length of the splice. It picks up radio noise, like an antenna.
After replacing the splice with whatever they use now, the technician said that my neighbors and I have "green" signal to noise now. About 45 minutes after the guy arrived, I had great signal, a new modem, and no problems bouncing around the web.