Arris CM8200 DOCSIS 3.1 Cable Modem

The Arris CM8200A is the modem Cox itself deployed for its Gigablast rollout: a DOCSIS 3.1 Touchstone unit built to operator specifications rather than retail-shelf ones. That pedigree is exactly why it makes a strong refurbished buy. It handles gigabit cable plans with the stability of carrier-grade hardware, and because it is a pure modem with no WiFi or phone extras, there is nothing between the cable line and your router.

Pair it with any wireless router. The router runs your WiFi; the CM8200A runs the connection.

Quick Specs

Carrier-Grade DOCSIS 3.1

DOCSIS 3.1 is what cable providers use to deliver gigabit tiers, and it improves reliability along with speed. OFDM channels resist line noise and neighborhood congestion better than older DOCSIS 3.0 hardware, so throughput stays steadier during peak evening hours. On plans below gigabit, the CM8200A falls back to full 32x8 channel bonding, the maximum DOCSIS 3.0 configuration, so mid-tier plans get complete headroom too.

Built for Operators, Priced Refurbished

Unlike retail modems designed for store shelves, the CM8200 line was engineered for ISP deployment, with the RF performance and diagnostics operators demand before they will put a device in customer homes by the thousands. Buying one refurbished gets you that hardware standard without the retail markup, and without a monthly rental fee on your bill.

Simple Setup

Connect the coax line, power it on, plug your router into Ethernet Port 1, and activate through your provider's app or a quick call with the modem's MAC address. No technician visit required.

Will It Work With Your Internet?

The CM8200A is best matched with Cox, which deployed this model for its Gigablast service and still documents it in official support materials. Mediacom ended support for this model in October 2024, so it is not the right choice for Mediacom accounts. It is not a fit for Xfinity or Spectrum, whose approved lists favor retail models like the SB8200. Approved-modem lists change periodically, so confirm this model against your specific plan with Cox before ordering. Our activation guarantee applies as always: if your provider will not activate it, the return is on us.

Frequently Asked Questions

Does the CM8200A have WiFi?

No. It is a modem only. Connect your own wireless router to Ethernet Port 1 and use whatever WiFi hardware suits your home.

Why are there two Ethernet ports?

The second port exists for operator configurations like link aggregation and business deployments. On residential service, providers activate Port 1 only, so plug your router there. The second port sitting unused is normal.

What plan speeds does it support?

Plans up to 1 Gbps. The active gigabit Ethernet port delivers around 940 Mbps of real-world throughput, which matches gigabit cable tiers. For 2 Gbps and faster multi-gig plans, you need a modem with a 2.5 Gbps port, such as the Arris S33.

Does it work with Cox?

Yes, Cox is this modem's home turf. It was deployed by Cox for Gigablast service. Confirm with Cox that your specific plan supports customer-owned equipment before ordering.

What is the difference between the CM8200 and CM8200A?

The letter suffix denotes a hardware revision. The models are functionally identical and are treated as the same device by providers.

Does the refurbished unit come with a warranty?

Yes. Every refurbished device we ship is tested, factory reset, and covered by our 90-day full-coverage warranty, plus our activation guarantee on modems.