works great, just have too many. A new and improved version of the world's most widely deployed DOCSIS cable modems. For the residential cable subscriber who wants a powerful modem capable of delivering a high-speed data service at blazing fast speeds.10 / 100 / 1000 Base-T Ethernet Port (RJ-45). *Requires CABLE Internet Service, if not sure your provider is CABLE call them to confirm *Compatible with ALL Major CABLE providers like Comcast, Cox, Charter, Time Warner, Mediacom, Bright House Building upon the success of the SB6120, Motorola's SURFboard SB6121 delivers your complete personal media experience, at lightning-fast broadband speed. It harnesses the power of DOCSIS 3.0 technology to bond up to four downstream channels and four upstream channels--providing you advanced multimedia services with data rates of more than 100 Mbps in each direction. That makes gaming, shopping, downloading, working, high-quality voice and video conferencing, and peer-to-peer networking applications far more realistic, faster, and efficient than ever before. The SB6121 is compatible with the following operating systems: Windows 7 Windows Vista, Service Pack 1 or later Windows XP, Service Pack 2 or later Mac 10.4 or later (Ethernet connection only) UNIX (Ethernet connection only) Linux (Ethernet connection only) Please understand that the Arris/Motorola Certified Refurbished Modem you are purchasing may have been previously set up with your Cable Internet Provider. We make the best effort to ensure the MAC ID is purged from that Provider’s database as part of the refurbish process, BUT occasionally they are not. If you get one that can NOT be activated due to the MAC ID, then please email Arris/Motorola and they will promptly exchange your modem.