are no longer supported by Comcast. Comcast refused to enable this "End of Life" modem for new accounts. I had to buy another DOCSIS3.0 modem. This is a list of their supported modems: http://mydeviceinfo.comcast.net/
RCA DCM425 Digital Cable Modem
9 Review
TP-Link Archer CR700 - 16x4 AC1750 Wi-Fi Cable Modem Router πΆ with 680Mbps DOCSIS 3.0 - Certified for Comcast XFINITY, Spectrum, Cox, and More
9 Review
π Zoom DOCSIS 3.0 Cable Modem 5341-02-03H: Fast and Reliable Internet Access
9 Review
MikroTik hAP AC Lite Tower RB952Ui-5ac2nD-TC Wireless RouterBoard
42 Review
π StarTech.com NETRS232 Serial to IP Ethernet Device Server - DIN Rail Mountable - Serial Device Server - Serial Over IP Device Server (Black)
4 Review
π uni USB C Hub with Ethernet Adapter, 4K HDMI, Gigabit Ethernet, and 3 USB 3.0 Ports for MacBook Pro, iPad Pro, XPS
11 Review
π CERRXIAN RS232 to Ethernet Serial Device Server - TCP/IP Converter with 1Port DB9 RS232 Serial to Ethernet Connectivity
3 Review
π StarTech.com NETRS2321P: 1-Port RS232 to Ethernet IP Converter, Serial over IP Device Server - Black
5 Review