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For Xfinity 800 Mbps service, the ARRIS SURFboard S33 is a strong standalone-modem option on Xfinity’s published compatible-device list: it is marked recommended, supports DOCSIS 3.1, and is rated for up to 2.33 Gbps wired download. It does not include Wi-Fi, so you’ll need a separate router. Before buying, check the exact model in Xfinity My Device Info for your address, plan, and voice services. A modem’s listed maximum is a device capability, not a guarantee of your actual speed.
What modem do you need for Xfinity 800 Mbps?
You need a modem Xfinity currently approves for your address and plan, with support for your subscribed speed. Xfinity’s guidance is straightforward: “Your modem must work with Xfinity and support your internet speed.” Check eligibility in My Device Info before purchasing; compatibility and speed support are separate checks, and results can depend on the address and services on the account.
Xfinity’s compatible-device list dated March 6, 2025 identifies the following DOCSIS 3.1 devices as recommended or suitable options for this speed range. The wired download figures are the capabilities Xfinity publishes for each model, not guaranteed speeds for every customer.
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|---|---|---|---|
| ARRIS SURFboard S33 | Standalone modem | Recommended; DOCSIS 3.1; up to 2.33 Gbps wired download | People who want to choose a separate router |
| Netgear CAX30 | Modem-router gateway | Recommended; DOCSIS 3.1; built-in Wi-Fi; up to 949 Mbps wired download | People who prefer a single modem-and-Wi-Fi device |
| ARRIS SURFboard SBG8300 | Modem-router gateway | Recommended; DOCSIS 3.1; built-in Wi-Fi; up to 941 Mbps wired download | People who prefer a single modem-and-Wi-Fi device |
| ARRIS SURFboard T25 | Standalone voice-enabled modem | DOCSIS 3.1; telephone enabled; up to 949 Mbps wired download | Xfinity Voice customers after confirming eligibility |
These details come from Xfinity’s March 6, 2025 compatible-device list. Device approvals and service features can change, so use the account-specific lookup rather than treating a published list as permanent approval for every location.
#1 Best Overall
- ⚠️ CABLE INTERNET ONLY - NOT COMPATIBLE WITH: Fiber (Verizon FiOS, AT&T), DSL, Satellite, or Fixed Wireless. ONLY works with cable providers like Xfinity, Spectrum, Cox. Verify your internet type BEFORE purchase.
- 🚫 NO WiFi INCLUDED - ROUTER REQUIRED: This is a modem ONLY. You MUST buy a separate WiFi router to get wireless internet. Without a router, only ONE device can connect via Ethernet cable. This does NOT replace your current WiFi router.
- 🔌 CABLE INTERNET REQUIRED: Works EXCLUSIVELY with cable internet service (DOCSIS) from providers like Xfinity, Spectrum, or Cox. Will NOT work with fiber (Verizon FiOS, AT&T), DSL, satellite, or fixed wireless internet. Contact your ISP to confirm compatibility BEFORE purchasing.
- 🚀 MULTI-GIG PERFORMANCE: Supports internet plans up to 2.5 Gbps with 2.5 Gbps Ethernet port. Designed for plans 1 Gbps and faster from certified providers: Xfinity (up to 2.33 Gbps), Spectrum (1 Gbps), Cox (2 Gbps). Verify your plan speed and provider compatibility.
- 💡 SETUP REQUIREMENTS: You need: (1) Cable internet service, (2) Separate WiFi router with 2.5 Gbps port for full speeds, (3) ISP activation. This modem cannot create WiFi networks or connect multiple devices without additional equipment.
Is DOCSIS 3.1 needed for Xfinity 800 Mbps?
The listed candidates above use DOCSIS 3.1, the cable-modem standard shown for these recommended options in Xfinity’s device list. The practical buying test is not the standard name alone: confirm that Xfinity lists the exact model for your address and that it supports your subscribed tier. The lookup is especially important if your account includes voice service.
Should you buy a modem or a modem-router gateway?
Choose the S33 if you want separate devices
The S33 is a modem only. You will need a separate router to create a Wi-Fi network, and you can choose or replace that router independently. This setup can make sense if you already own a suitable router or want to select Wi-Fi equipment separately.
Rank #2
- Mid/high-split DOCSIS 3.1 cable modem delivers up to 2Gbps of download speeds and 1Gbps of upload speeds
- Unlock faster cable internet speeds, such as Xfinity’s 900Mbps download speeds and 100Mbps upload speeds. Works with all major US internet providers. Not compatible with Xfinity Voice plans
- Faster download speeds powers your digital lifestyle with enhanced speed, capacity, efficiency, and response times
- 10x faster upload speeds for seamless multi-family gaming, video conferencing and uploading even the largest files—simultaneously. Plus provides easy remote access to your home security cameras and files on your NAS
- For the ultimate in performance, link a NETGEAR WiFi 6E or WiFi 7 router or Orbi system to the CM2500 cable modem
Choose a gateway if you want Wi-Fi in the same unit
The CAX30 and SBG8300 combine a modem and Wi-Fi router in one device. That means fewer boxes and no separate router purchase, but your home’s Wi-Fi coverage still depends on the gateway’s placement, the layout and size of the home, and interference. A gateway’s listed wired rating does not establish the wireless speed you will see in every room.
What if you have Xfinity Voice?
Voice service changes the compatibility check. Xfinity’s device list distinguishes voice-enabled equipment; the ARRIS T25 is listed as voice telephone enabled, while the S33 is presented as a standalone modem without that designation. If you subscribe to Xfinity Voice, verify that a specific model supports your exact voice service in My Device Info before ordering. Do not assume an internet-compatible modem will also support phone service.
Rank #3
- MAXIMIZE YOUR CABLE INTERNET AND WHOLE-HOME WIFI: A cable modem and WiFi router in one device unlocks the full potential of your home internet with faster downloads, smoother WiFi for gaming and video calls, and reliable coverage in every room.
- APPROVED FOR YOUR PROVIDER AND PLAN: Works with Xfinity internet plans up to 800Mbps, Spectrum up to 1Gbps, and Cox up to 1Gbps. Not compatible with Verizon, AT&T, CenturyLink, DirecTV, DISH, or bundled voice plans. ISP activation required after setup.
- MULTI-GIG DOCSIS 3.1 SPEEDS: Get Gigabit+ cable download speeds on today's fastest plans, with headroom for the upgrades ahead. Real-world speeds depend on your plan and ISP network.
- WIFI 6 COVERAGE FOR THE WHOLE HOME: Stay connected in every room with dual-band AX2700 WiFi 6 covering up to 2,000 sq ft and capacity for 25+ connected devices. Real-world coverage depends on home size, layout, and building materials.
- WIRED CONNECTIONS FOR YOUR FASTEST DEVICES: Four Gigabit Ethernet ports keep gaming consoles, desktops, and streaming devices hardwired for the lowest latency and the most stable connection in your home.
Will a modem rated above 800 Mbps deliver 800 Mbps?
Not necessarily. The S33’s “up to 2.33 Gbps” figure is Xfinity’s published wired-download capability for that device, not a promise that your connection will test at that speed—or even exactly at 800 Mbps. Xfinity says actual speeds vary and are not guaranteed. Factors include your device, whether you connect by Ethernet or Wi-Fi, Wi-Fi interference and congestion, destination networks, and modem performance.
For a fixed device such as a desktop or game console, Xfinity says a wired Ethernet connection will usually perform better than Wi-Fi where possible. For Wi-Fi devices, distance from the router, walls, interference, and other network activity can affect results.
Rank #4
- ⚠️ COAXIAL CABLE INTERNET ONLY - NOT FIBER: This modem works ONLY with Internet delivered through coaxial cable (the round cable with screw-on connector). Even if you have Xfinity, Spectrum, or Cox service, verify you have their CABLE internet service, NOT their fiber optic service. Check your wall connection before purchasing. Will NOT work with fiber internet (Verizon FiOS, AT&T Fiber, Google Fiber), DSL, satellite, or 5G home internet. Verify your internet type BEFORE purchasing.
- ⚠️ NO WiFi, NO Voice, NO Router Features: This device ONLY connects to your cable line and provides ONE Ethernet port. It does NOT create WiFi networks, has NO phone/voice capabilities, and cannot connect multiple devices without a separate WiFi router.
- 🔧 REQUIRED FOR SETUP: (1) Cable internet service (not fiber), (2) Separate WiFi router with 2.5 Gbps port for full speeds, (3) ISP activation call. Without a router, you can connect only ONE device via the single Ethernet cable included.
- 💰POTENTIAL RENTAL FEE SAVINGS - While some providers have reduced or eliminated modem rental fees, this modem can still provide cost savings and performance benefits. Check with your provider about current rental fees before purchasing.
- DOCSIS 3.1 TECHNOLOGY - Supports cable internet speeds UP TO 1 Gbps with advanced DOCSIS 3.1 performance. Perfect for streaming, gaming, and multiple devices when paired with your WiFi router.
Is the 800 Mbps plan available at your address?
Availability and plan names can vary by location. Xfinity’s network-management data lists an 800 Mbps tier among plans available for purchase as of April 9, 2024, but that historical table does not establish that the tier is currently offered at every address. Check current offers and your account before buying equipment for a particular plan.
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The same disclosure reports historical median download measurements for the 800 Mbps tier: 922 Mbps at peak and 931 Mbps off-peak for both HFC/DOCSIS sub-split and mid-split connections. Those are published measurements associated with the table’s stated plan period, not a present-day speed guarantee or a prediction for an individual subscriber. See Xfinity Network Management and Xfinity Internet Broadband Disclosures for the provider’s disclosures.
Quick Recap
Best Value
- ⚠️ CABLE INTERNET ONLY - This modem works ONLY with cable internet providers (Xfinity, Spectrum, Cox). NOT compatible with fiber internet services including AT&T Fiber, Verizon Fios, Frontier Fiber, Google Fiber, or CenturyLink Fiber. Check with your ISP to confirm you have cable (coaxial) service before purchasing.
- 📞 DATA ONLY - NO PHONE SERVICE - This modem does NOT support telephone or voice service of any kind. If your internet plan includes phone service or you need VoIP calling, you must purchase a separate voice-capable modem or VoIP adapter. This device handles internet data only.”
- 🚀 MULTI-GIG PERFORMANCE: Supports internet plans up to 2.5 Gbps with 2.5 Gbps Ethernet port. Designed for plans 1 Gbps and faster from certified CABLE providers: Xfinity (up to 2 Gbps), Spectrum (1 Gbps), Cox (2 Gbps). NOT compatible with fiber internet services. Verify your plan speed and provider compatibility.
- 🔌 MODEM ONLY - NO WIFI INCLUDED - This device is a cable modem with ONE Ethernet port only. It does NOT provide WiFi or wireless connectivity. You MUST connect your own separate WiFi router to this modem to create a wireless network. This is not an all-in-one gateway or combo unit.
- ⚡ DOCSIS 3.1 TECHNOLOGY: Latest cable standard with 32x8 channel bonding for reliable multi-gig speeds. Backward compatible with DOCSIS 3.0 networks. Eliminates monthly modem rental fees (typically $14-20/month). For CABLE internet only - verify compatibility with your cable provider.
How to choose before you order
- Check your address and plan: Open Xfinity My Device Info and confirm the exact model is eligible for your service.
- Confirm voice support: If you use Xfinity Voice, verify phone-service compatibility for the exact modem and account.
- Pick the device format: Choose a standalone modem such as the S33 if you want a separate router, or a listed gateway if you prefer integrated Wi-Fi.
- Plan for wired connections: If a computer, console, or other fixed device needs the most dependable performance, make sure your setup can connect it to the router or gateway by Ethernet.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
