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
MikroTik hAP AC Lite Tower RB952Ui-5ac2nD-TC Wireless RouterBoard
42 Review
Netgear DM111P Broadband Wired ADSL2
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 CERRXIAN RS232 to Ethernet Serial Device Server - TCP/IP Converter with 1Port DB9 RS232 Serial to Ethernet Connectivity
3 Review
π Juiced Systems Silver BizHUB USB-C Multiport Gigabit HDMI Hub with 3 USB 3.0 Ports, Gigabit Ethernet, 4K HDMI, SD/Micro SD, and USB-C Power Delivery
11 Review
UGREEN USB 3.0 Ethernet Adapter Hub with RJ45: Fast Gigabit Ethernet Converter, 3 Ports USB 3.0 Hub Compatible for MacBook, iMac, Surface Pro, Chromebook, Laptop, PC
11 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