Many continue to pay Comcast and other wired internet service providers, which are constantly increasing monthly fees for renting cable modems. But with some research you can buy your own modem directly and save money in the long run.
The benefits of renting a cable modem are that you can approach your hardware support ISP, including Wi-Fi help if your modem includes a wireless gateway, and the company will replace the modem for free if the device fails or cannot support higher network speeds , as it upgrades its service or moves to a faster level. However, given the typical monthly rental fees, the premium you pay for these benefits will be high compared to the cost of purchasing your own modem in almost every case.
For example, if you pay the cable company $ 1
But you should read the bill carefully before continuing. Some cable companies have chosen to stop charging a rental fee altogether and hiding it in the monthly service bill. TidBITS Publisher Adam Engst checked the bill and found that his supplier, Spectrum, was one of them. (In 2016, Charter Communications acquired Time Warner Cable, its former ISP, and has now rebranded all services under the Spectrum name.) That means there is no savings for him if he buys his own modem.
Select the fastest model  Wired Internet service depends on the DOCSIS standard (Data Over Cable Service Interface Specification), which was developed over two decades ago. Version 3.0, which was released in 2006, provided massive increases in maximum downstream and upstream prices, leading to cable expansions in the DSL DSL service.
DOCSIS 3.0 was in many ways so far ahead of its time that it remains in active and heavy use. The maximum downstream speed is 1.2 Gbps and upstream circuits at 200 Mbps. Version 3.1 was shown in 2013 with 10 Gbps downstream and 1 or 2 Gbps upstream maximums. A further improvement from 2017, 3.1 Full Duplex, provides up to 10 Gbps for both upstream and downstream data.
Get DOCSIS 3.0 and later modems provide maximum possible data rates for their respective supported versions. Performance is based entirely on the type of modem chips installed, which configure network communication over the coaxial cable section to "channels." Each channel is actually its own separate data stream, and the modem binds all channels together invisibly to you. More specifically, each channel has a maximum amount of data it can carry, and total throughput is based on either the number of channels built into the modem or how many cable carriers support your account. (DOCSIS 3.0 and later has a surprising amount in common with Wi-Fi.) You can have a modem that can surpass your connection, which is good, or a connection that offers more channels than your modem can handle, which is poor.  With DOCSIS 3.0, devices can be configured with as few as four downstream channels and an upstream channel labeled as 4 × 1 or 171 Mbps downstream and 43 Mbps upstream. In practice, most 3.0 modems began on 4 × 4 and 8 × 4 (343 Mbps / 171 Mbps) models. In particular, a DOCSIS 3.1 modem cannot offer less than 24 × 2 or 1 Gbps / 123 Mbps. (DOCSIS 3.1 has more capacity per channel for upstream signals, and therefore 3.0 and 3.1 upstream bandwidth vary per channel.)
As with Wi-Fi, you don't see the maximum real-time throughput rate they describe a state of perfection that never exists. Cable wires may suffer from transient interference, line quality degradation, and speed drops due to long distances from the data termination point of the cable network connection. In addition, channels may suffer from overload if too many customers around you are connected to the same cable data segment in relation to the throughput they require. The modems automatically adjust which channels they use and the throughput of each channel based on continuous line and usage changes.
This means that your ISP must overdeliver on the number of channels it uses to provide you with reliable service up to the promised service level. If you have a 100 Mbps Internet subscription, the cable ISP modem does not allow only four channels, as "171 Mbps" would likely cost much less on average. As a result, you need a cable modem that overcomes your current level of service with a factor of two or three to ensure you have enough capacity to exceed some of the issues mentioned just above average. So a DOCSIS 3.0 modem with 8 × 4 (343 Mbps / 171 Mbps) should work well with a 100 Mbps / 20 Mbps broadband plan. But if you pay for 200 or 300 Mbps, you will have a much faster model. (Internet service providers will melt service in the modem – it is a function of the DOCSIS specification – or on the network side of things to ensure they do not give you more throughput than you pay for.)
With gigabit broadband service over cable, you have a DOCSIS 3.1 model, although some 3.0 versions support 32 downstream channels (about 1.4 Gbps). That's because cable gigabit service providers, such as Comcast, have chosen to deliver gigabit speeds only using 3.1 technology for greater efficiency and flexibility due to improvements that are invisible to customers, but which make a difference in delivering service.
Although DOCSIS 3.1 modems cost slightly more than 3.0 models – $ 160 to $ 180 for well-rated 3.1 models against less than $ 100 for 3.0 models – in most cases you should buy a 3.1 model, even if your current broadband speed does not guarantee it. Modems with 3.1 built-in are backward compatible with the 3.0 service and thus provide future protection against service upgrades without having to replace the hardware.
Although the DOCSIS 3.1 Full Duplex specification has been released, there are no consumer-level modems yet supporting it, and DOCSIS 3.1 offers more than enough throughput for consumers and most businesses. Ignore it for now.
Buy and install your own cable modem
Each cable company has a different list of approved "retail" modems that work on the network, making it impossible to offer a form recommendation. In addition, you may want to find a cable modem that contains other features, such as a Wi-Fi router, although it costs more than a "stupid" device that only knows how to connect the cable system.
Pay close attention if you subscribe to both broadband and voice service from your ISP cable. Cable operators usually restrict which modems they support for both broadband and voice, and you may need to purchase a modem through a partner or the manufacturer's website instead of through an online or brick dealer.
What do you want to pay? ?
- DOCIS 3.0 up to 300 Mbps broadband: around $ 60. NetGear CM500-1AZNAS (16 × 4 or 686 Mbps / 171 Mbps) is a great example, providing good reviews and working across almost all cable operators' networks .
- DOCIS 3.0 up to 600 Mbps broadband: around $ 100. Many choose the Arris SB6190 (32 × 8) for the highest data rates below 1 Gbps on DOCSIS 3.0 networks.
- DOCSIS 3.1 up to 1 Gbps broadband: $ 160- $ 180: With many choices for 3.1 models, consider the Arris SB8200 ($ 180) and the Motorola SB8200 ($ 160), which are solid performers in reviews.
Here is where to look at available modems for the best cable ISPs in the United States:
- Cox: ] A little technical site that starts with compatibility issues, meets you at Cox, but it goes down to a long list of compatible modems. A self-installation page guides you through activating a modem, which requires the serial number and the cable MAC address.
- Optimal and Suddenlink (Altice): Altice's two cable brands provide no public information on purchasing your own modem. Some third-party websites recommend modems for these vendors, but I suggest contacting customer service before purchasing.
- Spectrum (Charter): Spectrum's Authorized Devices on the Spectrum Network site displays modems that fit a visitor's postcode.
- Xfinity (Comcast): Xfinity takes the most encouraging approach with terrific advice on how and what to buy, and a dedicated My Device Info page that checks which service is available to subscribers who sign in and non-subscribers who gives his address. It even comes with a promise: "All listed equipment is certified and compatible with Xfinity Internet service." Xfinity also publishes a clear set of steps to activate your own modem, even if it is a bit more complex than other providers.
You can also turn to a trusted third party for reviews. Wirecutter assembled a set of recommendations for modems that deliver the performance most currently need: 24 × 8 with DOCSIS 3.0 for up to broadband service up to 600 Mbps and a 3.1 alternative for gigabit subscribers. The reviews dig into compatibility across carriers and other more detailed features compared.
Don't forget to get a receipt!
One of the worst parts of managing a cable business is that it ceases to bill you for services and hardware that you do not use and do not own. I went to a local Comcast office to return my rental modem a few years ago and made sure to get a receipt showing that I had handed it over.
And surely when the sun comes up in the morning, my next bill is still showing a rental fee. It took months to convince Comcast to stop charging me, even though the company eventually refunded all fees and "believed" me. I had a receipt!
If you need to return the rental modem via the mail or UPS, be sure to take pictures of the device when sending it, including the serial number and box, and send only in a way that provides a tracking number on the receipt.
Even when you think they can't get you, they will try. But in the end you do not pay a monthly fee anymore.