content: This is the real answer right here. For modems, you can't go wrong with the Surfboard line - they've been around for ages, they're solid, and they're fully certified by Comcast. For example: http://smile.amazon.com/ARRIS-Motorola-SurfBoard-SB6121-DOCSIS/dp/B004XC6GJ0 Then, you can get whatever routers, switches, or other networking stuff you need behind the modem. 802.11ac, gigabit LAN, whatever you think you need, you can upgrade just that component without having to purchase a whole new modem too. Edit: I should also note that the modem above is only going to get you up to about 100 Mbits - if you need to go higher, or want to future proof your connection, you'll probably want to step up to the SB6183, which is also Comcast certified: http://smile.amazon.com/ARRIS-Motorola-SurfBoard-SB6183-DOCSIS/dp/B00MA5U1FW