Him, I goaded into fetching a Wintel laptop. After staring at disastrous dropout rates for 15 minutes on that box, he was forced to concede the source of the problem, and remade the whole works for me, from pole to desktop. When there was still no connection, he attempted to commandeer a technician from System Maintenance, to no avail, except that I finally understood both what was wrong with my connection, and with Cablevision's tech support organization. The original, periodic failures I was experiencing were due to a bad physical connection somewhere between the pole in my yard and Optimum's servers. LAN experience has me guessing a bad board in a hub, a guess strengthened when a visiting technician let slip that some of my neighbors were having the same problem.
Bad boards can mean any number of things.
For example, heat buildup can cause a connector to warp, causing the connection to fail. Whatever is causing my problems was exacerbated by the modem switch, specifically because the addition of error correction interferes with the Mac OS's error correction protocols, giving the Mac the impression there is no connection at all, when in fact the modem is tying up the connection with requests for resends. Recently, wet weather has caused even the modem to concede defeat, indicated by the green connection light going amber, and a series of self-diagnostics which make for a mini light show. Once upon a time, Cablevision worked its way through the vagaries of providing a television signal through wires, found a system that was mostly reliable, and built an empire. When fiber optics became available, they were not among the first adopters, but when the Internet exploded, they quickly recognized a new source of revenue and got busy rewiring.