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Is your broadband speed being ‘throttled’?

The German research group Max Planck Institute reckons broadband speed ‘throttling’ is more prevalent in Britain than anywhere else in Europe. Is this another sign that Britain’s broadband is lagging behind?

When driving on the motorway it’s fairly common to see temporary speed limits in place, normally because of congestion, an accident or poor driving conditions. In any instance, these limits are there to ensure safety and prevent accidents.

What you might not appreciate is that internet service providers (ISPs) do a similar thing with broadband connections, and new research indicates that Britain suffers from ‘broadband throttling’ more than most other countries.

The worst in Europe?

Since 2008, Max Planck Institute has hosted a tool called Glasnost that aimed to detect broadband throttling on home broadband connections. It’s been used 1.5 million times since and, in an interview with the New York Times, the men behind the tool let slip that the UK suffers from throttling more than anyone other country in Europe.

Of the tests run from BT connections, 74% showed signs of throttling. Throttling also exceeded 50% on several other UK ISPs, including big names like Virgin Media and TalkTalk.

It’s important to point out that this doesn’t mean 74% of BT connections are being throttled – it’s an indicator that those who took the test, likely heavy users, were affected. However, most ISPs in France didn’t exceed 21% and Germany’s didn’t exceed 16% – a marked difference to what Brits are having to put up with.

Why is broadband being throttled?

Dig deep enough on the ISPs’ websites (you’ll need to dig very deep on some) and you’ll normally find out why Britain’s broadband is being throttled. Most, if not all, ISPs employ some kind of ‘throttling’.

Some call it a network or traffic management, and many users have dubbed it ‘shaping’. Whatever it’s called, the reason is simple – such policies exist to prevent heavy users from affecting the quality of service for other customers.

This is laudable and understandable, but the lack of transparency and consistency of these policies is concerning. Every company employs different policies, refers to them by different names and the details are often smothered in layers of technical jargon.

Consequently, it’s extremely difficult to compare ISPs, and there’s no way to independently verify if an ISP is even following the policy correctly or, indeed, enforcing it.

What do we think about throttling?

At Which? it’s our view that ISPs need to be upfront about their traffic management practices. It should be made clear at the point of purchase so that consumers can make informed choices, and be explained in such a way that we can all easily understand the implications.

Do you think you’ve been affected by broadband ‘throttling’ and have you read your ISP’s traffic management policy?


My ISP specifically says “no throttling” – plenty of the small ISPs offer packages with no throttling they just wont be as cheap as the “big players”.

Just as important as throttling is congestion due to inadequate bandwidth or lack of capacity.
This will show up with slower speeds in the evening peak periods.
Again the smaller ISPs will often offer a better service in this departments as well.

Calm down Andy – It’s only a communications system.
Roads are busy in the peaks, so are trains and buses. Surprise, surprise! Broadband is busy in the peaks. Things are slow from 08:30 – 09:00 as all the schools and offices open up but then it settles down. 16:00 – 17:30 shows congestion as children hit their pc’s. No big problem really – we don’t need to get stressed out over milliseconds.
Oh yes – let’s get all ISP’s to standardise their definitions and then let’s audit them and let’s publicise the results; and who’s going to take a blind bit of notice? – Fewer than one percent in my opinion. People who like Virgin go with Virgin; people who like BT go with BT. Knowing the throttling policy and checking its veracity is not on their agenda. Leave fractions to the vulgar.

Scott says:
25 March 2022

Like most people, I would like to agree with this, but, it is happening at all times of the day and not only at the times specified, this can also be said to be happening at night, so it is the broadband company throttling the speed and not only the times it is busy.

I disagree, John. Until we all put pressure on the ISPs they will continue to misrepresent what they are providing.

My ISP provides up to 24Mbps service and I usually achieve a 5Mbps download speed, sometimes up to 7Mbps. If they marketed this as 5Mbps or less I would be happy, but ‘up to’ represents little more than dishonest marketing.

Fair point, wavechange. They shouldn’t misrepresent their level of service. I hate ‘up to’ wherever it appears and automatically distrust the user.

Sadly there is not much we can do about it because they all seem to be playing the same game. I agree with your suggestion that ISPs should standardise definitions, which would help us compare services.

My broadband is slow, and keeps being interrupted. I though it was because of a cheap modem, so we got a larger, (we thought more powerful) Netgear. We still have the same problem. Upon inquiry at PCWorld/Currys we had about 4 differing advices. Yes – we have done what all old prople do when faced with this scenario – nothing.

I got broadband in my rented house at university from Virgin media – for the past five days or so, it’s been ridiculously slow. I can’t even load full webpages without having to click “refresh” several times, and as for downloading files, you can forget about it.

We paid extra to have a faster connection, because five online TV-watching students live here. It’s pretty damn rubbish that we can’t even have something that works – yet we pay out of our a***s for it. Definitely not using them again. I remember when we called tech support the first time, they said we should only call them after having bad service for two or more days. I wonder why. Perhaps it’s because they want to save money paying someone ten thousand miles away to read some useless instructions off a piece of paper, then to send a man round to swap the routers round, for that to do absolutely NOTHING.

Marcus Welch says:
12 July 2013

Your broadband is slow because a little known fact that if you download over about 1.5gb between 4pm and 9pm in the evening Virgin slows down your Internet to about 2Mb, you won’t find that in their marketing. I left Virgin for that very reason, when he kids came home everything crawled along, I found out that my daughter used to watch short anime films, as we went over our 1.5Gb we were slowed down until if memory serves me the next day, so guess what it was always slow, it was only when I queried it i got the info.
It’s meant to be unlimited, that doesn’t mean we will slow you down to a crawl if you use over the amount we deem excessive, they said the only way to get this restriction removed was to go with their 50Mb, but I notice that that is restricted as well although they let you have a few more Gb before they knob ble your speed, Virgin, don’t bother

stephen brooklyn says:
24 November 2021

im on 500 and i can deffo tell they throttle the s**t out of it

chao_xian says:
17 November 2011

The key thing here is *throttling*. The cynic in me believes that it’s all deliberate in order to create artificial demand for their un-throttled and expensive packages…

Bottom line is that “bandwidth or capacity” is what costs ISPs money, so for a cheap broadband service one has to expect speeds to drop at peak times due to congestion or throttling by the ISP to stop congestion ( same as having variable speed limits on some motorways rather than just letting everything snarl up).

Ah well – Welcome to Virgin Media – Use the Internet all day – I pay for 10 Megs – I get from 9.8 to 10 Megs consistently. – broken down twice since it was installed 20 (?) years ago..

My only problem is some individual websites are slow due to lack of resources of the website not bandwidth of the ISP. (slow servers etc.).

BT on the other hand was total rubbish.,

But there are “bandwidth hogs” who say stream HD video using vast amounts of the available bandwidth so restrict traffic – I don’t experience this on Virgin but notice this on friend’s computer systems.

Personally I wouldn’t object to “throttling” if it actually improved the use of the bandwidth available.

Frankly I do get tired of those who demand unfettered bandwidth but refuse to pay the cost of maintaining it.

I was also with BT for a while (far to long) and am now with Direct Save Telecom. I looked at Virgin Media for their package, but it was so complicated, that I eventually walked away. The packages were – it seemed to me – deliberately complicated and confusing. There were 3 simple parts we were looking at, and to get all 3 was expensive, but we could have alternatives, and there were about 6 alternatives, some of which didn’t have any of what we were looking for. That may be a slight exaggeration – but not by much. We also tried search engines; which were even more confusing, as each one had different preferences and packages. I will stay where I am, as the monthly charges are very nearly constant.

CaptKirk says:
22 January 2012

Virgin are pretty reliable and do seem to deliver speeds as promised (unlike most copper cable outfits). Hwoever I am beginning to sense that they throttle BBC iplayer usage.

I do find that BBC iPlayer downloads seem to be restricted at the BBC end sometimes.
Although normally a film/program downloads ( in WMP format) at 16 Mbps there are times when it appears to be capped at 5 Mbps.
However downloading 3/4 films at once will push the combined download speed upto my 16/17 Mbps max. This suggests that my ISP isnt throttling the download.

I’m with O2 (Which BB) which was up front the service was traffic managed. Fine with me for busy times or very heavy users but they did not say was torrents are throttled close to death. That’s not what I take TM to mean and nor did the rest of O2 users who bitterly complained when the policy was introduced, so I read. I was so annoyed about this hidden policy and another O2 wrinkle and its supine response that I complained to Ofsted for what it’s worth. What more can you do? And I for one do not accept that paying for a phone line and broadband is cheap, nor is Virgin cable.

Steve Burke says:
24 November 2011

Trottling is particularly important for those of us in rural locations where the maximum broadband speed is often very low anyway. For instance it is rare for us to be able to see any short movies on uTube or the BBC website at the best of times. At peak times it’s impossible.

We’d like to see the ISPs giving priority to those of us on slow connections. After all, we pay the same amount as customers in the cities, but get a worse service at all times.

Ofcom has revealed what it intends to do to tackle broadband throttling – nothing at the moment it seems. Is Ofcom approach too soft, have your say on our latest Convo: https://conversation.which.co.uk/technology/ofcom-internet-traffic-management-net-neutrality/

Where I live there is no Virgin service and no plans to introduce. The local exchange is old and outdated but because we live outside city areas it is not a priority. I work from home as increasingly do many others and the slow or interupted service is annoying. It matters very little who my ISP is as the infrastructure is not up to the job, this is where the money needs spent.

Chris Gough says:
30 November 2011

I had always thought that the relatively slow broadband that I measured at 5500 kbps was a limit imposed by my connection to the BT exchange. recently my ISP, Plusnet, announced an improvement in their own bandwidth and my measured speed has now risen to 7500 kbps which is around the maximum possible for my line. So improvement is possible and was previously limited by the ISP

Robert says:
11 February 2012

Do a simple broadband speed test.
Then reboot your router and try again the speed test again.
90 percent of the time you will see an improvement

I have done this many times and I cannot recall ever having seen any difference. It is a sensible suggestion, of course.

I reckon you have a problem with your router if rebooting regularly helps to increase speed.