ARRIS (S34) – Cable Modem – Fast DOCSIS 3.1 Multi-Gigabit Cable Modem, for Comcast Xfinity, Cox, Spectrum & More, 2.5 Gbps Max Internet Speeds, 1 Year Warranty – (No Built-in WiFi)

great unit
has been very reliable and delivers great speed. Definitely helpful to avoid xfinity rental of their equipment. I paired it with an Asus router and then two other asus routers set up as wifi mesh units. We now have excellent, reliable and fast coverage on both floors.

Efficient Modem Upgrade with Heat Concerns
I recently upgraded my modem to improve my upload speed, opting for this model based on positive reviews. This modem has performed well, allowing me to reach my current upload cap of 150 with ease. My download speed sits comfortably at 400, a task both this modem and my previous one handled without any issues. My internet service provider is Comcast/Xfinity.However, one aspect to be mindful of is its tendency to run quite hot. The metal connector of the cable can become hot to the touch, raising concerns about potential overheating issues. While the passive cooling system keeps operations silent, I can’t help but wonder if a fan would have been beneficial to prevent any heat-related issues in the long run.

Modem Underperformed—Xfinity Undermined Its Own Recommendation
Amazon was excellent—fast shipping, easy return, no complaints. This review is strictly about how Xfinity and the modem itself failed to deliver.I purchased the Arris S34 after receiving an email from Xfinity stating,“Your internet equipment can’t deliver the latest speeds… Find a compatible device today.”They linked to their own compatibility list, and the Arris S34 was clearly approved for my 1Gbps plan. So I replaced my reliable Netgear CM700, expecting better performance.Instead, speeds dropped, and the modem began flapping, frequent disconnects, slower throughput, and worse performance than the older CM700 it replaced. When I contacted support, Xfinity repeatedly claimed the S34 was “not recommended,” despite it being on their own list. They offered to send me their XB8 gateway and enroll me in their “Next Gen” plan, stating, “I can upgrade you to the new Gen plan, which offers 1000 Mbps + unlimited data for just $96.05, along with a new XB8 modem. You will also receive a $10 monthly discount if you enroll in Automatic Payments and Paperless Billing using your bank account.” That’s a price hike from my current $75/month—and they wouldn’t clarify what happens after the first 12 months.I asked that the S34 be removed from their recommended list. It’s misleading to approve a device publicly, then undermine it during support to push proprietary hardware.I’m returning the S34 and replacing it with a Motorola MB8600, which is also listed as compatible. If I’m treated the same way again, I’ll be switching to AT&T Fiber, which was recently installed in my neighborhood. At least they don’t play games with modem support.If you’re buying this for Xfinity, be warned: the modem underperformed, and the ISP experience was even worse.Update: After I received the Motorola MB8600, Xfinity again refused to support it—despite it being on their approved list—and pushed me toward their proprietary XB8 gateway with yet another offer for “better speeds” and “lower prices.” I declined. Meanwhile, AT&T pulled fiber directly to my home. I connected it to my TP-Link router without a hitch. No drama, no games. Just fast, stable internet

Good unit. Keep the manual for light meanings.
Solid and very compact DOCSIS 3.1 cable modem.Note this is a cable modem/cable-ethernet bridge only and does not include wireless connectivity and is not a router. You will need other devices that have a compatible twisted pair copper ethernet port to make use of it, such as a “wifi router” or other layer 3 device.Works perfectly with Cox Business cable plans, including the gigabit and higher options available as of March 2025.The ethernet port is mGig capable so you can actually utilize the higher speeds if the CPE you attach to it is also mGig capable.Three minor pain points lost a star for me (really 1.5 but we can’t do half stars and it’s not a 3):1. Most importantly, there is only the one status light on it, which you can see on the front in the product image. It is multi-colored, so it indicates its status via the color and whether or not it is blinking in whatever color it is at the time.What are the colors? What do they mean? Apparently Arris doesnt thonk its important enough to make permanently obvious on the unit. What the various states that light can be in are not indicated anywhere on the unit and they’re not exactly intuitively obvious, so you have to look it up in the manual just to know what it’s telling you. Since that is kiiiiind of an important part of the setup process, it makes the first use experience a bit annoying. And that is especially true since you’ll be on the phome.with your ISP when they need to know what state it’s in, but they don’t know the meaning due to what I’m about to say on point 2, and you probably already threw the box outside for tomorrow’s pick-up, didn’t you? Go get that manual or find it online (which isn’t easy, so go get the paper one) before you call them. You’re welcome. And then what happens the next time there’s a problem and you call tech support? Yeah. If you do nothing else with the manual, tear out that page and tape it to the bottom of the unit or on your router or something.2. This is inexcusable for a product that is on the shelves and should have been done before then: Cox and Arris need to do whatever they do to “certify” this model and list it on their internal and public support knowledge bases as a supported model. It’s been out more than long enough for that and the process to get an unlisted but still perfectly compatible unit (like this one) is anything but smooth, and will take a hot minute or 20.3. WHY can’t anyone include the MAC address(es) and serial number on a sticker you can place somewhere convenient like in the manual or on the front of the device? If it’s not in a convenient spot (and let’s face it – your cable modem is crammed in a dark and barely reachable nook isn’t it?), you’ll want to be sure to take a picture of the label on the back of the unit before you call to activate it with your ISP, since they’re going to want those. And every ISP does, because thats how they know what account it’s for. So this should seriously just be standard by now. 😆Overall, a great little unit. Just the paper cut issues above make it less plug-and-play than it could have easily been.