Cable Modems Frequent Questions

These are some of the most popular questions we get about cable modems. If you have a question, feel free to use the comments section below.

What Modems Are Compatible With XFINITY by Comcast?

There are a lot of cable modems approved for use with Comcast. Basically, any ARRIS or Netgear modem will work. However, you have to be sure that you have the correct one for your subscribed speed. View a list of compatible modems by tiers on our XFINITY Modems page.

What Is The Best Modem For XFINITY?

The Netgear CM500 is the best standard cable modem for XFINITY services. It is approved for tiers up to 300 Mbps, has great feedback, and is relatively cheap at around $60. For the best WiFi or XFINITY Voice Modems, visit our main page. 

Does Comcast Sell Modems? – #1 Modems FAQ

No. Comcast will rent one to you if you elect to do so for a forever-going monthly fee. It is much cheaper to buy a new cable modem of your own.

Can I Buy My Own Modem For XFINITY?

Yes, you certainly can. As stated above, it is cheaper and you can save on your monthly Comcast bill. We can help you find a modem best suited for your needs here. ​

What Is The Difference Between A WiFi Cable Modem and A Regular Modem?

A standard cable modem can only be used with a single PC, a separate router, or another device.  ​A WiFi modem, a.k.a. modem router combo or gateway, has a built-in router that can be used to connect to many devices throughout the home, either wirelessly. Internet signals can also transmit through a wired connection via the Ethernet ports on the back of the WiFi modem. ​We can help you find the right cable modem for your service and speeds here. 

What Is The Best Cable Modem?

Based on reviews, # of sales,  ease of installation, and price, we elect the Netgear CM500 as the best cable modem of 2021. The Netgear CM500 is approved by most cable providers and at tiers up to 300 Mbps. Most households have 300 Mbps or lower which makes the CM500 the most compatible cable modem. Read more about the Netgear CM500 Cable Modem.

What Does “End of Life” Mean On My Modem?

An “End of Life” cable modem means that at one point a modem was recognized as a compatible modem. It may now be unstable for many reasons to work on a network. It may have reached the end of production, may no longer be supported by the manufacturer, use outdated technology, or other reasons. Obviously, “End of Life” modems should no longer be purchased. However, some sellers still sell them. To avoid buying an End Of Life modem, or soon to be, buy a DOCSIS 3.1 modem.


DOCSIS is short for Data Over Cable Service Interface Specification. DOCSIS is a system built by the top cable modem companies. It was defined to allow higher transmission of internet speeds for users who subscribe to cable internet. The latest, and most used today is the DOCSIS 3.0 platform. However, DOCSIS 3.1 and Full Duplex DOCSIS 3.1, have been developed and equipment is in the early stages of production and/or getting ready for retail.

What is An Internet Modem?

An Internet modem is required by providers to receive their Internet services. The traditional cable wire coming into a home is connected to the modem. The signal is either distributed to a built-in router, a separate router, by means of wireless or wired technology. Most cable companies charge a per month fee to use their modem, however, you can buy your own modem and save on monthly rental fees. ​

What Is The Difference Between The ARRIS SURFboard SBG6700-AC & SBG6782-AC?

The SBG6700-AC has two built-in WiFi antennas and does not support MoCA networking. The SBG6782-AC has three built-in WiFi antennas and does support MoCA networking. Otherwise, both run on the same dual frequencies and have 8×4 channel bonding.

Why Am I Not Receiving My Subscribed Internet Speed?

Your modem may be to blame.  If your modem doesn’t have the correct number of download/upload channels for your tier, you will experience lag and slower speeds. Additionally, if the modem doesn’t have the proper download speed capabilities, you will also experience slow speeds.  You can test your Internet speed and equipment using Our Speed Test Tool.
Hint: A test of a wireless connection and a wired connection may show a need for a better WiFi modem or separate router. Most generally though you can expect at least a small decrease in speed over any WiFi connection compared to a wired connection.

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