Arris Surfboard S34 DOCSIS 3.1 Multi-Gig Cable Modem | 2.5Gbps + 1Gbps Ethernet Ports | Compatible with Xfinity, Cox, Spectrum | Next Gen Upstream | Modem Only, Router Required

I ditched my ISP’s rented modem the day I upgraded to a 1.2 Gbps plan and never looked back. The SURFboard S34 is a clean, no-nonsense DOCSIS 3.1 modem with a 2.5 Gbps Ethernet port plus a bonus 1 Gbps port for link aggregation if your router supports it. Setup took under 10 minutes (activate on Xfinity/Spectrum/Cox app or phone call), and it’s been rock-solid ever since—no random reboots, no overheating, just consistent multi-gig speeds. Pros: • Real multi-gig capability — Hits 1.4–1.8 Gbps actual download on gigabit+ plans (tested with my own speed tests) • 2.5 Gbps + 1 Gbps ports — Future-proof and perfect for bonding or separate devices • 32×8 channel bonding — Locks on strong even in crowded node areas • Cool and quiet — Stays barely warm, vents well, no loud fans • Own-your-modem savings — Paid for itself in under a year vs $14/month rental fees • Easy activation on major ISPs (Xfinity, Spectrum, Cox, Mediacom) Cons: • No built-in router/WiFi — Pure modem, so you still need your own router (most people do anyway) • Pricey upfront — Not cheap, but cheaper than renting long-term • Link aggregation needs compatible router — Not everyone can use both ports at once If you’re on a gigabit or faster plan and tired of rental fees or sluggish ISP gear, the S34 delivers exactly what it promises: fast, stable, multi-gig internet with zero drama. One of the best modem upgrades I’ve ever made—5 stars, no hesitation.

Easy setup with Comcast and works with 2.5GB downstream and 300MB upstream package. Paired with the top end Netgear Orbi mesh system. Reliable and very fast.

This Arris cable modem, is awesome it works flawlessly with my new Xfinity fiber internet. Would highly recommend.

Compact. Ease in setting up. Worked seamlessly with internet provider

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

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.

If you pay for anything over around 600 Mbps, you need a modem that allows you to tap all of that available bandwidth. I had a reliable SB6190 for many years, and during that time, Comcast/Xfinity slowly increased my bandwidth. My current plan is for 800 Mbps, and though the SB6190 is rated for gigabit, it struggled to deliver near my full quota. As soon as I replaced the old modem with the S34, I was getting well over 900 Mpbs on the gigabit port. Activating the new modem has come a long way, and I was able to do it in the Xfinity app in just a few minutes. Nice. I'm used to having lights to help diagnose any connectivity issues, but realistically, they don't really help much anyway. With a bridged modem, you basically just reboot it if there is a problem anyway. The simple colored LED works just fine and it looks nice. Internal logging is minimal, but could provide useful information if necessary. I'm pleased with the upgrade and accomplished my goal of getting the maximum bandwidth I've been provisioned. The S34 also has the 2.5 Gbps port if I ever decide I need more, so it is future-proofed. My router is also capable of 2.5 Gbps, as is my computer's NIC, but I don't realistically need that much Internet bandwidth at this point. It's nice to know I've got the hardware if that changes.

I've had this modem for a couple weeks now, and it's been great. It provissioned automatically for Xfinity's next gen upload speeds (500/100) using the App. There have been some reports of people having issues getting the new upload speeds on plans above 1Gbps, but it seems to be getting fixed. Just call customer service and ask them to update your billing codes so you get provisioned correctly. Personally, I'm not a fan of its small size or its seemingly low amount of ventilation grills. It does run a bit warmer than my previous modem (mb8600, that modem was bigger and had ventilation holes on both sides), but it's honestly not much of a concern as it seems stable and haven't had any drops so far. I'll update further in a couple months when I upgrade to a higher tier. Overall I'm satisfied with the modem. Its closest competitor, the coda56 seems to be a decent alternative for most, but hitron's 6m warranty put me off a bit. The s34 comes with a 2 year warranty, which gives the impression that arris feels more confident about the longevity of their product.