Cable television interference

When helping out my parents move their modem/router that I installed from then for Xmas, my mom informed me of the 800 or so cable outlets around the house. Needless to say, figuring out what went where was difficult, but I finally managed. Turns out, outside the house, off the pole, is a 2-way splitter, that has been painted over and is really mounted to the house well. One line wraps around the house and one line goes into the house. That leg is hooked up to an amplifier, and then goes back outside. On the wall, there is a mounted splitter with 5 more legs coming out, wrapping around the house to various places. After finding the end of the data leg, and pulling it down through the floor into the basement, the router/modem was set up and worked well. Both the laptops got good signals, but whenever there was any sort of network activity, it produced lines of interference on the cable TV signal. I checked all the connections again, and everything seemed tight and exactly as it was before the big move. This happens on all the legs that have gone through that amp. Any ideas of what this means, and any tips how to address it? I know my folks won't stfu until I fix it.