Xfinity-Compatible modems for use with Apple router

We got an AirPort Extreme a few years ago to improve the WiFi signal of our Comcast/Xfinity router/modem. Since we don’t use the Xfinity WiFi function, I looked into replacing the modem portion with a compatible non-Xfinity modem, since they charge $14/mo rent on the device, and this would be a one-time purchase. But our local installer says he’s never had success trying to get a supposedly Xfinity-compatible modem to work with the service.

Xfinity does list recommend devices on its Website.

We have 2nd-tier service to deliver 4K streaming to our ROKU box. Does anyone have experience using one of these compatible modems in this way?

Paul Brians
Bainbridge Island, WA

A couple years ago we had no choice but Comcast and I knew I wanted to keep using my AP Extreme. I bought a Netgear CM500 cable modem on Amazon for $87 (at the time). On arrival, I plugged the coaxial cable into the box and it worked pretty much right away. I definitely didn’t need Comcast’s help to get it to run. I think at the time it was listed on a Comcast site as being compatible.

It was a cheap plasticy crummy little modem, nothing fancy, but it did what it was supposed to. It wasn’t fast either, but still faster than the downlink Comcast promised so I was OK with that. To be honest, that part never gave me any grief. A lot of other Comcast shenanigans did so as soon as I could I dumped them for fiber (Sonic) and have been happy ever since. Comcast operates like the mob. I vowed never to do business with them again. Ever.

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By the way, for less than what I paid back in the day, you can now get what Wirecutter says is the best cable modem, a Motorola MB7621 for $78. Their runner up is the successor to the Netgear modem I bought a few years ago. And their budget recommendation is actually the model I bought.

Just be sure you are using a modem that meets the appropriate Docsis standard. Below gigabit, Docsis3.0 should be fine, but if you have or anticipating upgrading soon to gigabit level, you will need a modem compatible at the Docsis 3.1 level (note that higher level compatibility implies lower level compatibility. I used a Surfboard SB6190 until my service level went up. I am currently using a NetGear CM1000 that I got on sale with no issues. Note that what matters is the Docsis standard, not the speed rating on the box. Of course, I am noting modems which have Internet service only; very few of these commonly available modems also handle voice.

I got one of the recommended ones…Motorola something or other for our gigabit speed connection…and it worked out of the box just fine.

I’m using my own equipment with Comcast and have been doing so for several years. I also checked Comcast’s page for approved equipment, to ensure compatibility, but if all you need is Internet access (no voice or home security services), then you can probably ignore it and get anything that is DOCSIS 3.0 or 3.1 compatible.

In my case (remember, this was several years ago), I bought a Zoom model 5352 modem/router combo. This unit is no longer made, but for comparison purposes, it features:

  • DOCSIS 3.0
  • 8 downlink channels (max 343 Mbps)
  • 4 uplink channels (max 123 Mbps)
  • 802.11n Wi-Fi

It worked well for quite some time. Over the years, the Wi-Fi started getting flaky, so I put it into bridge mode (converting it to a dumb cable modem) and attached a Linksys MR8300 router for all my routing, gateway and Wi-Fi needs. The combination has worked very well for my Internet service (100 Mbps downlink, 6 Mbps uplink).

I would recommend, in general, to not get a combination modem/router, but get separate devices. Here’s why:

  • You probably won’t be replacing them on the same schedule. If they’re separate devices, you can upgrade the parts that need upgrading and keep the parts that don’t.
  • There’s a much much greater choice of routers than there are modems. Especially if you want to stick with a modem from Comcast’s list. By keeping them separate, you can use almost any router that exists.
  • This is probably the most important one. For some reason (I assume legal), you can not install your own firmware upgrades into a cable modem - your service provider (Comcast, in this case) is responsible for pushing updates into it. If your modem includes a router, then you can’t upgrade the router firmware either. It’s been my experience that Comcast really doesn’t care about pushing out firmware updates, which means it will end up being pretty old, buggy and probably full of security holes. You can’t do anything about the modem firmware, but if the router is a separate device, you can keep it up to date on your own.

If I were to recommend something today, I would recommend doing what you’re doing. Buy separate modems and routers. Buy a modem off of Comcast’s list of models recommended for your level of service.

In order to support future service upgrades, I’d pay a bit extra to get a high-end modem. Today, this means DOCSIS 3.1 support, with 32 downlink channels and 8 uplink channels. These will support up to gigabit speeds. When I visit Comcast’s page, they list the following modem-only (non-router) devices with those features:

  • Arris T25. About $200 at Amazon. Includes support for digital voice service, should you want it in the future.
  • Arris SB8200. About $150 at Amazon. No support for voice service
  • Motorola MB8600. About $160 at Amazon. No voice service.
  • Netgear CM1200. About $200 at Amazon. This model claims it can go up to 2Gbps if/when Comcast should start offering such service. No voice service.
  • Netgear CM1150V. About $240 at Amazon. This looks like the CM1200 plus voice service capability
  • Netgear CM1100. I can’t find this model on Amazon. No voice service.
  • Netgear CM1000v2. I can’t find this model on Amazon. No voice service.
  • Netgear CM1000-1AZNAS. About $160 at Amazon. No voice service
  • Netgear CM1000. I can’t find this on Amazon. I don’t know if it’s the same as the CM1000-1AZNAS

I can’t recommend any of these because I’ve never used any of them. I would do some web searching for product reviews, eliminate those that have bad reliability and buy the least expensive model from what’s left.

As for your installer being unable to set up third-party modems, that just proves he doesn’t know what he’s doing. It’s trivially simple.

Plug in the modem and attach a computer to it. Either connect directly (making sure your computer is running firewall software!) or via your router. Go visit a web page (I suggest Comcast’s home page).

You’ll find that every page you visit redirects to a Comcast sign-on page (much like hotel Internet service). Log on using your Comcast user ID and password. Comcast will authenticate you and automatically register your modem with the service. They will then (probably) push firmware and configuration data into the modem. Let it do this. It will probably take a few minutes. Once completed, the modem will reboot and you’ll be on-line.

Now go attach your router and configure it the way you want in order to let your whole LAN access the Internet.

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I would certainly recommend sticking with a model shown on their compatibility page, mostly because they are responsible for firmware updates and will only do so for models currently on the list. My model dropped off the list a few months back and they notified me that I would need to change it because it was no longer being supported by Motorola/Arris. When I called last week regarding a problem with my TV, they refused to help me until I got a new modem (which obviously has nothing to do with my cable TV service). I went ahead and swapped it for a Motorola SB8600 anyway, because I had upgraded to gig internet (at a cost savings) and I could tell my Internet had become flaky.

Thank you for all the detailed advice. Unfortunately we do very much need voice. We use our VOIP phone all the time.

Paul Brians

Not a problem. If you’re subscribed to Comcast’s voice service (where analog land lines plug into your modem), then just make sure to buy a modem with voice capability. When I did a search for top-tier modems (those capable of gigabit speeds), two (the Arris T25 and the Netgear CM1150V) include this feature.

If you’re using some other VOIP solution (e.g. Magic Jack), then you can use any modem. Those services all run over your Internet connection.

When we upgraded to Xfinity gigabit I had a hard time finding a DOCSIS 3.1 modem that would also work with their voice so I bought the item below and split the coax feed to the new modem and my old voice modem. Works fine.

Down here we only have Cox or crappy. They want 14$US per month to rent a modem. So when I saw a used one on NextDoor I bought it, an SBG6900. It worked straight away and I returned their’s. The previous owner forgot the admin password so I had to do a hard reset but otherwise it was fine and has been working ever since.

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That hard reset is a good idea, even if you got the admin password. You don’t know how it was configured on the previous owner’s network. It might have configuraitons you don’t want (e.g. MAC address security filtering, parental controls, etc.)

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Your local installer doesn’t get out much, it seems.
I’ve used non-Comcast-provided modems and routers for years.
Current modem is ARRIS SB6141 DOSCIS 3.0 and ASUS RT-AC66U router, and Apple AirPort Extreme before that. Just pick a unit that’s VOIP compatible, count your savings, at least until Comcast/Xfinity hits you with another increase in one or more of their “fees.”

I’ve been using the Netgear Nighthawk CM1150V Docsis 3.1 Cable Modem for the previous five months ($229 from B&H Photo) with my Xfinity service, and it has worked fine. I previously used my own modem, but it was Docsis 3.0. Since I am now getting faster internet speeds, I decided to upgrade to Docsis 3.1. The problem was finding a Docsis 3.1 Cable Modem with voice. This was the first one I found. I’ve had no problems at all since I installed it.

The only downside is the cost. At $229, the payback vs. rental is longer than I’d like, but there are few choices and they’re all expensive at the moment. I’m sure the price will drop once there are more choices.

I’ve been using the Netgear CM600 modem with Comcast/Xfinity service in Lake Stevens, WA for some time now, it works great! It’s connected to a Netgear R8500 router, then to Mac, other wired stuff, and too many wireless devices including a Roku Ultra (4k). Also using a T-Mobile VOIP device, all no problem. Can’t speak to Apple router, but I can’t imagine any issues. The router shouldn’t care what modem it’s connected to. Hope this helps.

I just recently returned to Xfinity after seven years with AT&T UVerse. I was very happy with ATT but the prices kept creeping up.

I didn’t want/need any of the “features” of the Xfinity modem so I found one on markdown at Amazon. The reviews were good so I ordered it. I did a self-install and within 10 minutes of plugging it in I was up and running. My plan is for the 100MBit internet and with over provisioning and this modem I’m usually achieving 106-112 MBit. It’s only needed one reboot in one month. (Very good for Xfinity)

If I were still doing business with Comcast, I’d advocate that you explicitly copyright that wonderful post and somehow make money selling it to their customers.

One reason I’d do so is that most of their customer’s aren’t told that Comcast is making money from the combination modem/router they’re making the customer pay rent to use, (via their public WiFi hotspots that are embedded into equipment they put into the customers’ homes)! If we had an FCC that cared about the customer rather than the giant corporations, that business practice would be illegal.

And, as to the resourcefulness of the typical Comcast installer, it’s all over the map. There are excellent ones, and there are some who don’t even read the scripts they use for a vanilla installation.

When we lost our home in the 2017 Sonoma County wildfires, we found a home to rent in the hamlet of Penngrove, just south of Santa Rosa. Penngrove has a rural post office. The USPS maintains an enormous address database that Comcast and many delivery services use to “find” customers. In unincorporated hamlets with rural post offices, there may be a street address posted on your door or on the entrance to your property, but so far as anyone who uses that database is concerned, your address doesn’t exist.

The house we found was smack dab in the middle of town on Main Street. It was a WONDERFUL house, on property that previously had housed a giant farmhouse but which had been subdivided by a local builder about a decade earlier. He’d refurnished the farmhouse and built 3 new houses on the property, all of which shared a common driveway. An attractive and easily visible sign at the mouth of the shared driveway bore all the addresses, easily readable from vehicles

When we moved in, I called Comcast, went to their store to pick up my cable box/DVR combo (NO router/cable modem - I use a DOCSIS 3.1 Arris modem). On the appointment day, I stayed home from work; no one showed up; no one called.

So, I called Comcast. Their customer service agent told me they couldn’t find me; there was no such address in their database. I reminded the service agent that I’d provided a phone number (she confirmed it AND that I was using that number to talk with her), and I prevailed on her to type my address into Google Maps, which of course revealed Satellite and Street View images of my rented home. She noted my record and we set up a new appointment, but on the next install date, no one called, no one showed up.

The cable “drops” from the utility poles on main street in Penngrove on the subdivided property are to a manifold partially shielded from public view by some bushes and some gorgeous gigantic redwoods. My house was between two others, and both of my neighbors turned out to be Comcast subscribers; both told similar horror stories about obtaining service. So, I called customer support again, while standing outside in front of the manifold, behind the bushes partially obscuring me from Main Street, which ran by right in front of our houses at the bottom of the shared driveway. Once I oriented the agent , I made a suggestion: she could either make certain a knowledgeable installer actually showed up to do the work, or I could create a need for THREE work tickets with two snips of my garden shears.

After that, he showed up (but that wasn’t the end of the nightmare).The path from the manifold to the utility interface closet on the side of my house went under my concrete driveway; the builder had thoughtfully run PCV pipe the entire distance, but the Comcast Installers couldn’t figure out how to run their coax through that piping. Without my iPhone’s WiFi hotspot, we would have had no internet service at home for more than a month. Eventually, the builder/owner had to run the coax for them. It took him just a few minutes.

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I’ve given up on this project while isolation is in effect, but I was delighted to see your post because I’ve never seen anybody mention Penngrove before. In the ’40s and ’50s I grew up in a house one mile north of Penngrove, went to school and church in Penngrove, delivered papers in Penngrove. When people ask where in northern California I’m from I usually say "Do you know where
Sonoma State College is? because nobody knows where Penngrove is.