Below is a list of Comcast/Xfinity approved retail devices that can be used in lieu of rental equipment. This is not an official list but is compiled and maintained by the community. Please visit https://mydeviceinfo.xfinity.com to verify that a specific device will work with your service. If you find an error or information that needs to be updated, please feel free to send me a private message. Thank you!
Modem: This is the basic device you need to connect your home network to Comcast. A modem will provide a single ethernet connection. Most people connect the modem to a router in order to have more than one wired device and WiFi service. Some modems provide voice capabilities.
Gateway: Many people don't want to deal with a separate modem and router. A gateway device is a combination modem and router. They typically allow four wired connections and provide WiFi. Some gateway devices also provide voice capabilities.
Channels: These are communication paths. The more channels the better. This is expressed as downstream channels x upstream channels. So a device that is labeled "32x8" has 32 downstream channels and 8 upstream channels. Higher speed tiers require modems with more channels. Each channel can handle ~25Mbps, therefore an eight channel modem would be capable of ~200Mbps.
Netgear CBR40 32x8 gateway (Orbi)
DOCSIS 3.1 Devices (required for gigabit speeds)
Motorola MB8600 32x8 modem (DOCSIS 3.1)
Arris SB8200 32x8 modem (DOCSIS 3.1)
Netgear CM1000-100NAS 32x8 modem (DOCSIS 3.1) Note: The CM1000-1AZNAS is not supported.
Netgear C7800 32x8 gateway (DOCSIS 3.1)
Voice Capable Devices
Arris TG862G 8x4 gateway telephony (Same as TG862G-CT, TG862G/CT)
Last update 7/4/18 @nerdburg
Thanks to @darkangelic for proofreading.