Cable modems need a strong signal in order to operate properly. The more splitters you pass through successively degrades the signal strength (-3.5dB/splitter). For a while internet service was working fine, but then I would loose the external ip address every no and then. I then investigated the wiring in the house, and it turns out there was silly decisions made. There was a splitter in the basement going to nowhere, with at least 25 feet of cable. I removed the splitter and put in a direct coupler, but the problem persisted. I then moved the modem to the other line split off the main. This required reworking of the entire network and the implementation of a network switch. The minimum amount of splitters, the modem must pass through, is two. The first splitter provides service to downstairs and upstairs. The second splitter provides television to my father tv and the modem. I replaced the second splitter in the sequence, and am moving toward replacing the splitter sending signals to downstairs and upstairs. If I replace the main splitter, which is located outsite, and the problem persists, I will be calling Cablevision for the installation of a completely separate main line coming into the house; this will bypass all splitter and give the maximum signal strength possible.