Complex sentence: The SPA3102 connects to the LAN socket, on the modem, and then the computer, which was previously connected to the modem, now connects to the LAN connection on the SPA3102.
Split into simpler sentences: The SPA3102 connects to the LAN socket on the modem. The computer, which is traditionally connected to the modem, now connects directly to the LAN connection on the SPA3102.