What affects broadband speeds?

broadband connection types© Choose

THERE is more to broadband speeds than the headline, as anyone who has battled for bandwidth come 6 o'clock can attest.

It's easy to get angry at our provider but sometimes other factors can be at play - including how far you live from the local telephone exchange; the type of broadband connection you have and the quality of those cables; and how your home is setup and the router you use.

Of course, providers can be at blame for slow broadband too - including network congestion and fair use policies and we'll look at these issues too.

Read on to find out what could be affecting your broadband speeds.

Actual vs advertised speeds

Before getting into the factors that make up the whole picture on broadband speeds, however, it's important for us to look at why we don't have the whole picture in the first place.

The answer lies in how speeds are advertised and the difference between those adverts and how speeds are actually measured.

How broadband speeds are measured

Broadband speeds are measured based on the number of megabits (basically, blocks of data) downloaded using the connection per second.

On our site we always write this as Mb. Elsewhere, however, you may also see it written as Mb/s, Mbps or even meg.

Speeds under 1Mb are measured in kilobits (Kb) per second: 1Mb is 1024Kb. Speeds over 1024Mb are measured in Gigabits (Gb) per second: 1Gb is 1024Mb.

A broadband speed test will measure both a download speed - which will affect the time it takes to see web pages - and an upload speed - which will affect the time that it takes to upload information, say, photos to a Facebook album - that the connection is currently reaching.

In both cases, the speed test is a snapshot of speeds at a particular point in time.

While it can provide an indication, a single speed test can be unrepresentative of a connection's average capacity and it won't show some aspects of traffic management which mean that some online activities could be slower than others.

Most providers now slow peer-to-peer (P2P) software at peak times, for example, while others may prioritise gaming traffic.

How broadband speeds are advertised

For some time now, broadband speeds have been advertised as 'up to', meaning a speed that at least 10% of broadband users can achieve.

As people have been saying for years it's an unsatisfactory system and the Advertising Standards Agency look to be finally taking note with revisions expected very soon.

Currently, in Ofcom's broadband speeds voluntary code of practice they say:

"...it is critical that all ISPs explain to consumers that actual throughput speeds are likely to be lower than the headline or advertised speeds..."

So ISPs must also give potential customers an estimated line speed based on the available information about their line and postcode area.

It's the estimated line speed provided at the time of sign up that broadband customers should refer back to if they're trying to get their broadband up to speed, although it's still only an estimate.

What causes slow broadband speeds

When slow speeds are frustrating it's nice to have someone to blame and it can be easy to focus our attention on our provider.

We've yet to hear of a broadband user who hasn't suffered from slow broadband speeds at one time or another, however it's not always the provider at fault. Regardless, we've listed out the top reasons for slow broadband and we explain why they can cause a problem.

#1: Broadband connection type

The truth is that one of the most important factors when estimating broadband speeds - the most important for many users - remains the infrastructure of the broadband connection.

There are five main types of broadband connection in the UK:

broadband connection options

The fastest - FTTH - is currently only available in the UK from smaller providers including Hyperoptic or Gigaclear and locations are limited. BT and Virgin Media also offer trials but again it's not widely available.

Both Virgin Media and providers using BT's fibre network offer FTTC services with nationwide coverage.

The difference between these networks is partly the providers' decision and partly down to the 'last mile' cables they use: Virgin uses coaxial cable and BT still connect to homes through the original copper phone lines.

Standard broadband - offering up to 17Mb speeds - uses the copper phone line network for the entire journey from the telephone exchange. And it's because of this - distance becomes a big problem for those living in more remote areas.

#2: Where you live

The further away a property is from a telephone exchange the weaker broadband signal can become and the slower the actual connection.

This is due to a combination of attenuation, the signal getting weaker as it moves further away from its source; the quality of the lines themselves and electromagnetic background 'noise' which interferes with the signal.

Fibre optic cable broadband from Virgin Media is less prone to attenuation and noise problems which is why it's so much faster than other broadband services.

When people compare broadband by speed, for example using one of our comparison tables we filter out services that aren't available at the local exchange - in other words leaving the fastest broadband packages available at the postcode provided.

However, only the providers can give a more specific estimate about how well the line should work.

#3: Your provider

Intuitively, the best way to throw some broadband blame is at your service provider: after all, you are paying them.

As we noted above, there's a degree of truth to this.

Not only does the provider affect the cables available (see above) and the hardware and contention ratio (below) they can choose to affect connections directly.

Many so-called unlimited deals actually impose a fair use policy on their users.

People who breach the ISP's fair use policy will be 'throttled': simply this means that broadband speeds are slowed to prevent a small number of users from slowing the service down for everyone else.

Most providers' fair use policies only slow the very heaviest downloaders, you can check your ISP's policy here.

In addition, during busy times, usually evenings during the week and afternoons and evenings at the weekends, some providers manage or shape their internet traffic.

In general, downloads, and in particular peer-to-peer (P2P) activity, tend to be slowed during these peak periods.

Many of the biggest ISPs have, however, now relaxed their traffic management policies, while some have abandoned them altogether, most recently Plusnet.

Almost all broadband providers publish details of their traffic management policies and we cover them here so be sure to have a good read of these before signing up to a new deal to see how your web activity might be affected.

#4 Router and home setup

Often overlooked but broadband speeds can be greatly affected by how your home network is setup and the router you use.

Placing a wireless router downstairs in the living room, and then connecting over wi-fi in the loft room will provide a much slower connection than if you were closer to the router or connected to it using cables instead.

The more walls a wireless signal has to pass through and the greater the distance, the weaker it becomes.

Where you place your router and the cables in your home can have a big impact on improving broadband speeds.

Additionally, the wireless router itself can have an affect.

Newer wireless routers will be using the new 802.11n protocol - which means, while they are back compatible, if the wireless card in your computer or laptop was bought a few years ago and only supports 802.11b/g then you won't benefit from the speed boost and greater range of a wireless 'n' router.

And many of the more expensive routers or hubs also have added features such as automatic channel management, which means they will automatically switch to the least used channel to reduce interference from other nearby networks.

For more on how to check your router see our guide to ways to improve broadband speeds - available here.

#5 Network congestion

The number of people connecting to the Internet at the same time in your local area can have an impact on how fast your broadband is.

Home broadband connections are usually provided with a contention ratio of 50:1 - that means 49 other people will be sharing the same connection as you - and when all these people come online at the same time - which is more likely to happen during peak hours - the network can get congested and slow down.

Peak broadband time is often defined as being between 8pm and 10pm - when people come home in the evenings and are most likely to either stream TV or play games.

Unfortunately there's little we can do about having to share the Internet or that most people log on in the evening. However, if this is the most likely cause of slow broadband, switching to a faster broadband deal may well be the best bet as a dip in speed during peak times is less likely to affect your overall connection on a 50Mb package than it would if you were on 17Mb one.

But be warned, even the fastest packages can be hampered at these times, and actual speeds may be quite a bit slower than those advertised. For this reason, the Advertising Standards Agency is looking to make providers advertise their speeds for peak times.

Yet generally, higher speed packages are the way to go.


23 August 2014

Thanks for the answer.

13 August 2014

Hi, I'm working on the "contention ratio" in broadband internet, would you be so kind to tell me what is the contention ratio in those 5 services mentioned above? How can I get more information from you?

22 August 2014
Choose team

Typically, an ADSL provider's contention ratio used to be 50:1. But we don't actually know the contention ratios of individual providers because they tend not to publish them any more. We think this is because providers have been able to install more capacity (backhaul) at exchanges so there's more differentiation between places and also because fibre, which isn't affected by contention on the exchange level, has become more prevalent.

Sorry that's a bit of a vague answer.

1 May 2014

#1 - half of the story. Yes the cables feeding your pole (or underground directly in a lot of cases) greatly affect your speed, but so does many other factors including your home wiring.
If you have extensions fitted, are using cheap plug and socket extension cables and have connected your router to one of these then the line loss will increase and therefore broadband speed with drop. Equally, houses that use multiple sockets and have fitted the wiring themselves generally have not done it correctly and end up with a 'star wired' or 'backfed' system at their house.

3# 'Not only does the provider affect the cables available' - erm, no. No provider is responsible for the cables from the exchange to your house. That is the sole proviso of Openreach.

6# - contention ratios may, at one time, have been 50:1 for residential customers, but that is far from being the case now with SOME providers at SOME locations. 140:1 and 200:1 can be found at certain exchanges.
Couple this with a DSLAM (broadband equipment in an exchange) having a max throughput of 256mb/s and that being shared with up to 900 customers and you can see why your speed may be lower. (It is unlikely that all 900 ports would be in use, but is possible).
Rule of thumb - you get what you pay for.

#7 REIN, you've skipped over this entirely. Repetitive electrical impulse noise. Essentially noise created by an electrical component like a power supply, or anything that uses electricity, that can induce noise into the cable delivering broadband to your modem.

So what should you do? Yes, pick an ISP with a low contention ratio, but check out your own house.

Does the cable from the pole (or underground) go directly to the socket that your modem is plugged into?
Are there any junction points in your house? (small oval or rectangular boxes) and do they show any sign of corrosion/damp - green coloured irregularity.
Is your line noisy? From small crackles or wooshing noises to 'I can't hear you' noise. A lot of people don't even have a home phone these days, but worth borrowing a phone for a quick check. Noise over the dial tone or during a call will indicate a problem.

Do your own REIN check - tune a radio to 612khz AM/MW. If you hear noise near the cabling that feeds your modem you may have REIN interference. A change in volume as you move the radio will indicate the source - louder it gets the closer you are. Try turning all electrical appliances off first to get a base level to start with.

Call your ISP. They can run checks on your line to identify if any simple faults exist. If it comes back as OK, then ask if they can check your broadband speed and compare it with any of their other customers in the area.
If you've got the money, ask for a broadband engineer to improve your line - chargeable investigation, but you may just end up with faster speeds if your ISP will book an engineer for you.

9 May 2014
Choose team

Thanks for your comments - we didn't put electrical interference in to keep things simple, can't cover everything, but we hope other readers find your comments useful.

To address #1, I think we make clear later on in the article that a number of factors affect speeds. Point #3 is a good one, though. That was poorly worded and has now been corrected.

Thanks again!

28 August 2012

This is a very well composed article. Easy to read and understand. Thanks Julia.

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