Arris (S33-RB) DOCSIS 3.1 multi-gigabit cable modem
Quick take
The Arris (S33-RB) is a DOCSIS 3.1 cable modem designed to replace your ISP rental, offering two Ethernet ports and support for up to 2.5 Gbps downstream. It tends to work well when your provider fully provisions the modem, but upload performance can be constrained by ISP settings (a recurring theme for Xfinity mid-split upload expectations).
Pros and cons
Pros
- DOCSIS 3.1 modem technology for modern cable networks, with multi-gigabit potential (2.5 Gbps-rated Ethernet capability).
- Two Ethernet ports for connecting a router and another device (home lab and multi-router setups can be simpler).
- Generally straightforward activation when the modem is properly provisioned by your cable provider.
- Buyer reports frequently describe it as well-built and easy to monitor (signal and power level visibility).
Cons
- Not compatible with fiber, DSL, or satellite internet providers (for example, AT&T, Verizon, CenturyLink, Frontier, and similar services).
- Does not include Wi-Fi, and it does not support cable digital voice.
- Real-world upload speeds may be limited by ISP features and certification, particularly with Xfinity expectations.
- Buyer-review evidence is mixed on control and reliability details (some users report setup flexibility limitations, others report random failures in specific scenarios).
What buyers think
Buyer-review evidence is generally supportive of the modem’s core purpose: getting online quickly and delivering strong download performance when provisioning goes smoothly. Multiple reviews describe easy installation steps, good connectivity right away, and the ability to view useful status information like signal and power levels.
At the same time, the strongest caveats are compatibility and how your ISP configures service. A clear theme is that upload speeds can differ from download expectations, especially for Xfinity users who are aiming for higher upload tiers or mid-split behavior. There is also limited but notable negative evidence around software and configuration access (some reviews say the management interface is informational rather than fully editable), plus occasional reliability complaints that appear tied to particular network setups or firmware events.
Who this modem is for
Choose the Arris (S33-RB) if you have cable internet from a supported US provider and you want to stop paying a modem rental fee. It is a cable modem replacement, not a complete home networking device, so you will still need a separate Wi-Fi router.
It is a good fit for:
- Comcast Xfinity, Cox, Spectrum, or other US regional cable internet customers looking for DOCSIS 3.1 capability.
- Homes that benefit from multi-gigabit WAN links or want to use a high-speed router with a 2.5 Gbps-capable Ethernet port.
- People who want a modem they can monitor via its built-in web interface and status information.
Who should avoid it
This model is not the right pick if you are on a fiber, DSL, or satellite service, since it is built for cable internet. It also will not replace your phone service or eliminate the need for a router.
- AT&T, Verizon, CenturyLink, Frontier, Google Fiber, and similar non-cable providers.
- Anyone who needs built-in Wi-Fi or cable digital voice support.
- Shoppers who specifically require certain ISP upload features that may depend on modem certification or mid-split enablement on your account (especially if you are targeting higher upload tiers on Xfinity).
Key specs that matter in real life
- DOCSIS 3.1: Built for modern cable networks, with advertised multi-gigabit capability.
- Two Ethernet ports: Helps with a router plus another wired connection, or flexible cabling for small network labs (note that your router’s WAN port speed can still cap real throughput).
- Two-and-a-half gigabit rated download capability: Useful if your plan and router can actually take advantage of multi-gig speeds.
- No Wi-Fi, no voice: You will need a separate router (and separate phone service if you rely on voice).
Setup and activation: what to expect
Most buyers report a fairly standard process: connect the coax and Ethernet, power on, then activate through your provider’s app or activation flow. Success usually comes down to whether your ISP provisions the modem correctly and has it accepted for your account.
If you previously used a DOCSIS 3.0 modem, upgrading to DOCSIS 3.1 is often part of why this model is chosen, and some buyers report needing a careful power-cycle sequence for router and modem to re-establish connectivity cleanly.
Pros and cons, translated into buying decisions
Pros if you want faster cable downloads
For cable plans where download speed is the priority, the combination of DOCSIS 3.1 capability and multi-gig-rated Ethernet is aligned with what most shoppers expect from a “buy your own modem” upgrade. Buyer feedback commonly points to strong connectivity and good downlink performance once the account is provisioned.
The main tradeoff is ISP-dependent upload behavior
Some shoppers specifically notice upload performance limitations on Xfinity, describing blocked or reduced upload expectations tied to ISP network behavior and modem certification for certain upload configurations. If your plan emphasizes upload speed, it is worth verifying what upload features are enabled on your account for a customer-owned modem before you switch.
Control and interface expectations
Management features can be a deciding factor for network-curious buyers. Review evidence includes claims that the modem’s interface is more informational than fully configurable, and that advanced changes expected from other modem generations may not be available. If you rely on deep DHCP or security configuration at the modem level, you may need to plan to handle those settings on your router instead.
Verdict: is the Arris (S33-RB) worth it?
The Arris (S33-RB) is a solid option for cable customers who want a DOCSIS 3.1 modem for strong downstream performance and a simpler path to avoiding rental fees. It is most likely to feel “worth it” when your cable provider provisions it cleanly and you are not depending on specific high-upload features that may vary by ISP configuration.
If your top priority is upload speed (or you want specific Xfinity upload behavior), treat that as the biggest question to confirm before buying. If you’re mainly chasing multi-gig downloads and you have a compatible router with the right Ethernet port, this modem’s feature set aligns well.
Price and availability
This is listed as a renewed unit, and pricing can vary over time. If you care about value, compare the cost of a renewed modem against the rental fees you would otherwise pay, then factor in whether your plan and router can actually use the multi-gig capabilities.
Alternatives to consider
When comparing alternatives, focus less on the brand name and more on the category fit:
- Your ISP compatibility: Only buy a cable modem if you are actually on cable internet.
- Port speeds that match your router: Make sure your router WAN port can match the modem’s multi-gig Ethernet capability if you want those speeds.
- Upload feature requirements: If your ISP’s higher-upload setups depend on specific modem certification or network behavior, compare models that are known to work with your provider’s current configuration.
FAQ
What internet providers is the Arris (S33-RB) compatible with?
It is intended for cable internet providers in the US, including Comcast Xfinity, Cox, Spectrum, and other regional cable providers. It is not compatible with fiber, DSL, or satellite services (such as AT&T, Verizon, CenturyLink, Frontier, and similar).
Does the arris (S33-RB) include Wi-Fi?
No. It is a cable modem only. You will need a separate Wi-Fi router for wireless networking.
Does it support cable digital voice?
No. It does not support cable digital voice service.
How many Ethernet ports does it have?
It includes two Ethernet ports, including a 2.5 Gbps-rated port and an additional gigabit Ethernet port.
Will I automatically get the same upload speeds I see advertised for my plan?
Not necessarily. Upload performance can depend on how your ISP provisions your account and which network features are enabled for your modem. Some Xfinity users report upload limitations tied to mid-split behavior and modem certification.
Is a renewed (refurbished) modem a bad idea?
It can be reasonable if you want the hardware without the cost of an equivalent new unit. Buyer reports in this listing describe renewed units looking new and working as expected, though review evidence also includes occasional mixed reports about reliability in certain setups. If you switch providers or plan to use advanced network configurations, plan for a bit of troubleshooting time.
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Specifications
| Product Title | Arris (S33-RB) - Cable Modem - DOCSIS 3.1 Multi-Gigabit Cable Modem for Comcast Xfinity, Cox, Spectrum & More 1 & 2.5 Gbps Ports 2.5 Gbps Max Internet Speeds 4 OFDM Channels 1 Year Warranty - Renewed |
|---|---|
| Category | Electronics > Computers & Accessories > Networking Products > Modems |
| Brand | ARRIS |
| Manufacturer | CommScope |
| Model Number | S33 |
| Color | White |
| Connectivity Technology | Ethernet |
| Compatible Devices | Personal Computer |
| Number of Ports | 2 |
| Maximum Downstream Data Transfer Rate | 2500 Megabits Per Second |
| Maximum Upstream Data Transfer Rate | 2500 Megabits Per Second |
| Data Transfer Rate | 2500 Megabits Per Second |
| Number of Ethernet Ports | 2 |
| Internet Service Provider | Charter, Comcast Xfinity, Cox, Most Regional Cable Internet Providers, NOT compatible with ATT, Verizon, Centurylink, Google Fiber, Suddenlink |
| Modem Type | Cable |
| UPC | 612572216828 |
| Mfr Part Number | S33-RB |
| Item Type Name | Docsis 3.1 Modem |
| Unit Count | 1.0 Count |
| Warranty Description | 1 Year Limited Warranty |
| Built-In Media | ARRIS Surfboard S33-RB DOCSIS 3.1 2.5Gbps Cable Modem - Xfinity, Spectrum, Cox & More (RENEWED) |
| Internet service provider | Charter, Comcast Xfinity, Cox, Most Regional Cable Internet Providers, NOT compatible with ATT, Verizon, Centurylink, Google Fiber, Suddenlink Charter, Comcast Xfinity, Cox, Most Regional Cable Internet Providers, NOT compatible with ATT, Verizon, Centurylink, Google Fiber, Suddenlink See more |
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