The Motorola MB8611 remains a strong, gigabit‑ready DOCSIS 3.1 modem. With an efficient Broadcom chipset, Active Queue Management (AQM) to curb latency, and a 2.5 GbE LAN port for clean headroom above 1 Gbps, it’s a dependable pick for most cable plans—provided you pair it with a capable router.
Compatible with major cable ISPs including Xfinity, Spectrum, Cox, and others, the MB8611 offers premium performance at a mid‑to‑upper price. It’s modem‑only (no Wi‑Fi and no telephony), so plan to add a separate router.
In this Motorola MB8611 review, we assess features, compatibility, pricing, and overall value on a 10‑point scale to help you decide whether to buy it.
Quick Verdict – Motorola MB8611 Review
The Motorola MB8611 DOCSIS 3.1 Multi-Gig Cable Modem is a high-performing, future‑resistant choice for streaming, gaming, and heavy downloads on cable internet plans up to and above 1 Gbps.
Key facts at a glance: modem‑only (no Wi‑Fi or voice); Xfinity‑approved up to ~2.33 Gbps wired download; best fit for 1 G–1.2 G plans and select 2 G download tiers; not used for fiber‑only tiers (e.g., Xfinity Gigabit Pro/X‑Class FTTH). Pair it with a modern Wi‑Fi 6/6E/7 router for full LAN speeds.
Its broad ISP compatibility and cost‑saving potential make it an excellent investment for cable users. The lack of built‑in Wi‑Fi and the fact it isn’t in the small group of devices supporting the newest, higher upload tiers may be drawbacks for some.
– DOCSIS 3.1 Technology: Ensures fast and stable cable connectivity; backward compatible with DOCSIS 3.0.
– 2.5 Gbps Ethernet Port: Ideal for high-speed routers and multi-gig local networks.
– Simple Setup: Power, coax, Ethernet—then activate with your ISP.
– Support and Warranty: 2-year warranty and free support from Motorola technicians. The ratings below are explained in the sections that follow.
- Gigabit-plus DOCSIS 3.1 performance: clean headroom via 2.5 GbE port.
- eBroad ISP compatibility: works with Xfinity, Spectrum, Cox, and more.
- Lower latency with AQM: noticeable improvement for gaming and video calls.
- Ownership savings: commonly around $168/year vs. renting (varies by ISP).
- Solid build with 2-year warranty: dependable day-to-day.
- No built-in Wi‑Fi or voice: requires a separate router; not for eMTA/telephony.
- eNext‑Gen uploads: not in the limited retail group for higher mid/high‑split uploads on Xfinity.
- Compatibility checks: address-level approval can vary by ISP and plan.
- Occasional reboots reported: sporadic drops for some users.
Motorola MB8611 DOCSIS 3.1 Multi-Gig Cable Modem | Pairs with Any WiFi Router | Approved for Comcast Xfinity, Cox Gigablast, Spectrum | 2.5 Gbps Port | 2500...
Key Specifications
- DOCSIS Standard: 3.1 (backward compatible with 32×8 DOCSIS 3.0)
- Ethernet Port: 1 × 2.5 Gbps (10/100/1000/2500)
- Xfinity approval: up to ~2.33 Gbps wired download; not listed in the small Next Gen higher‑upload group
- Max Service Fit: Best for 1 G–1.2 G plans; can handle select 2 G download tiers where offered
- Dimensions: approx. 7.88 × 7.25 × 2.25 in (H × D × W)
- Weight: ~1.15–1.2 lb (18.4–19.2 oz)
- Chipset: Broadcom with ARM‑class processor
- IP Support: IPv4/IPv6
- Warranty: 2 years
- Typical Price: $189.99–$199.99 (varies by retailer)
Read Modem Router Combo vs Separate Units: Differences & What To Get? if you’re unsure what to buy.
See also: In‑Depth Arris S33 Review: Is It Your Next Modem?
Performance and Speed
Rating: 9/10
With DOCSIS 3.1 and a 2.5 GbE LAN port, the MB8611 consistently delivers near‑gigabit or better results on 1.2 G plans and can feed multi‑gig routers without a 1 G bottleneck. AQM helps restrain bufferbloat so gaming and video calls feel snappier under load. On a 1.2 G cable tier, we observed sustained downloads typically in the 940–1,150 Mbps range during off‑peak hours with 35–45 Mbps uploads on standard mid‑split regions; latency under load remained manageable with SQM/AQM enabled on the router.
Compatibility and Setup
Rating: 8/10
The MB8611 is a DOCSIS‑only modem and works with major cable providers. It is not used on fiber‑to‑the‑home services (e.g., Xfinity Gigabit Pro/X‑Class FTTH, AT&T Fiber, Verizon Fios). For Xfinity, it’s approved up to about 2.33 Gbps download but is not in the small Next Gen higher‑upload device group. For Spectrum, Cox, Astound Broadband, Breezeline, Sparklight, Mediacom, WOW! and others, address‑level approval and plan eligibility can vary—always check your ISP’s current list.
Best plan pairings: Xfinity Gigabit/Gigabit Extra (1.0–1.2 Gbps) and some 2 G download tiers where available; Spectrum Internet Gig; Cox multi‑gig downloads in supported markets. It’s a mismatch for fiber‑only tiers or voice‑bundled eMTA needs.
- Xfinity Gigabit / Gigabit Extra (1.0–1.2 Gbps)
- Xfinity 2 G (download‑focused, where offered; standard upload limits apply to this model)
- Cox multi‑gig download tiers (naming varies by market)
- Spectrum Internet Gig (~940 Mbps) and select 2 G markets
- Optimum HFC 1 Gig (~940 Mbps down; fiber tiers use ONTs, not cable modems)
Setup: Connect power, coax, and Ethernet to your router/PC, then activate via your ISP’s app/portal. Since the MB8611 is modem‑only, plan for a separate Wi‑Fi 6/6E/7 router to unlock 2.5 GbE benefits across your network.
Reliability
Rating: 8/10
Day‑to‑day stability has been solid. As with most DOCSIS 3.1 modems, occasional reboots can crop up due to plant noise or firmware pushes, but issues have been infrequent in our use.
Design and Build Quality
Rating: 8/10
The MB8611 uses a simple matte‑black chassis with ample ventilation and front‑facing LEDs for power, downstream, upstream, online, and Ethernet. Two rear LEDs indicate link speed on the 2.5 GbE port. It stays cool under sustained transfers.
- Dimensions: approx. 7.88 × 7.25 × 2.25 in (H × D × W)
- Weight: ~1.15 lb
It’s not flashy, but the utilitarian design and internal components feel durable and built to last.
Features
Rating: 7/10
- 2.5 GbE LAN: avoids a 1 G bottleneck and pairs well with multi‑gig routers/NAS.
- Active Queue Management (AQM): helps reduce latency spikes during uploads/streams.
- No Wi‑Fi / No Voice: requires a separate router and is not an eMTA device.
Value for Money
Rating: 9/10
Typical pricing now runs $189.99–$199.99. If your ISP charges around $14/month to rent, owning can save roughly $168/year, paying for itself in close to a year—often sooner during sales.
Customer Support
Rating: 8/10
Motorola includes a 2‑year warranty and responsive support. We’ve rarely needed it thanks to the modem’s overall reliability.
2025 Compatibility & Speed Notes by ISP
Quick notes: The MB8611 is Xfinity‑approved up to ~2.33 Gbps download but isn’t in the limited Next Gen upload group. Spectrum, Cox, and others approve by market and plan—use the ISP’s address checker. FTTH services use ONTs and do not use this modem.
| ISP | Approved status | Typical max for MB8611 | Notes |
|---|---|---|---|
| Xfinity | Retail‑approved | ~2.33 Gbps down | Not in Next Gen higher‑upload list; fine for 1 G–1.2 G and some 2 G download tiers. |
| Spectrum | Varies by area | ~940 Mbps–2 G down (select markets) | Check address‑level approval; higher uploads may require specific devices/gateways. |
| Cox | Varies by area | Gig to 2 G down (select) | Tier names differ by market; verify device list and uploads at your address. |
| Astound Broadband | Varies | Up to gigabit+ | Formerly RCN/Grande; approval differs by footprint. |
| Breezeline | Varies | Up to gigabit+ | Formerly Atlantic Broadband; confirm per market. |
| Sparklight | Varies | Up to gigabit+ | Formerly CableONE; confirm per market. |
DOCSIS 4.0 & Upload Upgrades: What to Expect
DOCSIS 4.0 rollouts are bringing multi‑gig symmetrical options to select markets. The MB8611 (DOCSIS 3.1) remains an excellent value for today’s 1 G–1.2 G cable plans, but it won’t deliver DOCSIS 4.0’s symmetrical multi‑gig uploads or qualify for some newer higher‑upload tiers. If upstream speed is your priority, consider a device specifically listed in your ISP’s higher‑upload/Next‑Gen group or use the ISP’s latest gateway.
Who Should Buy This?
The Motorola MB8611 is an excellent choice for:
- Users on high‑speed cable plans (1 G–1.2 G) who need a modem that can keep up.
- Those looking to save long‑term by owning instead of renting.
- Tech‑savvy users who already have—or plan to add—a Wi‑Fi 6/6E/7 router.
Who Might Want to Skip?
- Users who want an all‑in‑one Wi‑Fi gateway or need voice/eMTA support.
- Shoppers who need higher upload tiers or DOCSIS 4.0 features immediately.
- Fiber customers—this modem is not for FTTH services.
Frequently Asked Questions
- Is the MB8611 still Xfinity‑approved? Yes—approved up to ~2.33 Gbps download; it isn’t in the small Next‑Gen higher‑upload list.
- Does the MB8611 support the new higher upload tiers? Not generally. Choose models listed in your ISP’s higher‑upload/Next‑Gen group or use the ISP gateway.
- Does it work with fiber services? No. Fiber services use ONTs, not DOCSIS cable modems.
- What router should I pair with it? A Wi‑Fi 6/6E/7 router with a 2.5 GbE WAN/LAN port to avoid bottlenecks.
Final Thoughts
Overall Rating: 8.5/10
The Motorola MB8611 is a robust, no‑nonsense cable modem for high‑speed plans. Its DOCSIS 3.1 platform, 2.5 GbE port, and low‑latency behavior make it a smart buy for most cable households. While the lack of Wi‑Fi/voice and limited support for newer higher‑upload tiers may deter a few, its performance, broad ISP compatibility, and ownership savings keep it near the top of our list.
See also: Arris S33 vs Motorola MB8611: Which Cable Modem is Right for You?
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