Factors to consider

Can I choose my own modem?

Before reading this guide it should be noted that, depending what part of the world you live in and which internet service provider (ISP) you use, buying your own modem might not be an option available to you. In the United Kingdom for example, using third-party modems is generally not allowed by most ISPs (older model modems produced by the ISP in the past are sometimes allowed though), whereas in the United States of America it usually is, so be sure to check first before making a purchase. Assuming this is permitted, one also needs to check that the specific model in question is technologically compatible with your ISP.


This guide contains a mix of cable modems only along with combined modem-routers. Combined modem-routers are popular primarily because most people tend to prefer a simpler, more compact setup. However this can be a limiting factor in getting the most out of both your router and your modem as combined options sometimes sacrifice a degree of functionality compared to the separate units. Such a setup means both components must be upgraded as one, rather than being able to say retain a perfectly good modem component whilst purchasing a more secure router. This might mean higher costs long-term, but these might be outweighed by the extra convenience.

For a user guide on the factors to consider when looking at web routers, see:

Understanding internet speed

There are different factors which determine the speed of internet connection on any given system. The main three are: the limits set out in the package purchased from your Internet Service Provider (ISP), the bandwidth of your ethernet cable and the ports which connect your modem to your router, and the specifications of the modem itself.


DOCSIS (Data Over Cable Service Interface Specification) is the standard that’s used to measure the data capacity of the internet cables that transmit data and the amount of information a modem can process at any one time.

The current classifications of bandwidth are 1.x, 2.x, and 3.x. in ascending order of performance. A modem with a DOCSIS of 2.3 should have a greater potential speed than one with a rating of 2.1.

DOCSIS 3.1 and above also have another advantage: AQM or ‘Active Queue Management’ technology, which helps prevent the latency phenomenon known as ‘buffer bloat.’

Modem Channels

In addition to the DOCSIS number, the number of channels the modem has is also a determining factor. The majority of modems have either 4 or 8 ‘down channels’ (for downloading data) and 4 ‘up channels’ (for uploading).

A DOCSIS of 3.0 allows 43 Mbps (Megabits per second) max of downloading, therefore 4 channels will give you 4 x 43 = 172 Mbps max download speed, 8 will give you 8 x 43 = 344 Mbps and the upcoming 16 channel modems should permit up to 688 Mbps.

Other Limiting factors

Ultimately no matter how fast your modem is the max speed will still be limited to whatever web package you have bought from your ISP. Having a modem with a higher Mbps capacity than your subscription plan will help future proof it to a degree but also will cost more, so it’s a matter of personal choice which route makes the most sense.

In addition to this, the bandwidth of the ethernet cable (and socket/port) being used between the modem and the router can be a source of bottlenecking, so make sure this is the same as or greater than your internet speed.

Other factors


A consideration that applies really to all products, especially electronic technology. Make sure to read reviews online from other customers on Amazon etc. to see if any of them experienced any problems with their purchased model.


When accounting for reliability issues one should try and look for modems that come 30 day warranties at least. Most defects tend to manifest themselves in this period of use and a replacement ordered or a refund acquired. Some modems can come with warranties that last over two years but these are likely to come with a considerable markup premium, so it is up to the consumer to determine whether or not this would be worth the cost.


If desk space is an issue this could render some models unsuitable.

User Interface

A relatively minor consideration but a helpful user interface will assist in identifying the cause any problems that may occur with the connection. One should mainly check to see if there are any complaints in this area amongst customers regarding specific products.

What Consumers Say

Customer support

Standards of customer support can vary a lot between companies. If you have warranty protection this is less of an issue but if you are relying upon having relatively immediate internet access for work or other commitments, good customer support can remove a lot of headaches.

Surge protector

If maintaining a constant, interrupted link to the internet is vital, consider investing in a surge protector if you live in an area that experiences them, and use it to protect your modem, router, and computer/device.