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How we test wi-fi routers and extenders

By Hollie Hennessy

Discover how we assess wireless routers and extenders in our test lab. Only the cream of the crop earn our prestigious Best Buy award.

Put us to the test

Our Test Labs compare features and prices on a range of products. Try Which? to unlock our reviews. You'll instantly be able to compare our test scores, so you can make sure you don't get stuck with a Don't Buy.

Which? tests wireless wi-fi routers and extenders so that you know which one will give you the best wi-fi signal in your home. We put all the big-brand wi-fi routers and extenders through their paces so that we can help you choose one that's quick to transfer data, easy to use and offers decent signal strength.

Each wi-fi router and extender is subjected to the same set of gruelling tests so that we can compare them blow for blow. This means that we can answer your important, no-nonsense questions with confidence and give you a verdict you can trust. We’ll answer key questions about:

Head straight to our wi-fi router and extender reviews – or read on to find out more about how we test to answer each of these questions.

How good is wi-fi coverage and speed? 

To find out how well the router performs in terms of wi-fi coverage and speed, we use a variety of different tests. Firstly, we test how well the router or extender copes with different multimedia devices, including streaming 4K Netflix, YouTube, audio and online file transfer, running simultaneously around the home. This gives us our first indication of the coverage you'll get, and whether it will be possible to do a few things at once, under a relatively light load. 

But we don't stop there – coverage is also assessed by measuring exact speeds all around the test house. This shows whether the router or extender will give you decent speeds, even at hard-to-reach corners of the home. 

Finally, we test how well the router or booster will cope when there are lots of different devices connected, all requiring a lot of bandwidth. To do this, we transfer data on four different devices, all around the home, and record the file transfer speeds. This tells us how well the router is suited to homes with a lot of people, and whether it will conk out if you're trying to put it under a lot of stress – such as simultaneously downloading things online, streaming different Netflix shows around the house and gaming online, for example.

The below is a heat map that we get from our coverage testing. The greener the colour, the faster the signal is. 

Is the router or booster easy to set up? 

Wi-fi routers or boosters can sometimes be tricky to set up, so we assess how easy it is to get each device out of the box and up and running.

We note what instructions come with the router or extender and then assess how easy it is to set up for a beginner and whether it has more technical settings for advanced users.

We also look at how easy it is to set up a local network and apply parental controls.  

Are there any security issues? 

Your router is the gateway into your home, along with all of its devices, and we don't take this lightly. Our rigorous security and privacy tests are designed to uncover poorly designed or maintained products and apps that could put you and your data at risk.

We assess each router, mesh and extender – and their apps – to make sure that there's a good level of security in place.   

Utilising a combination of techniques, we assess each device for known issues and security vulnerabilities. We also analyse the data being captured and sent to ensure that your privacy is being protected along the way. 

No stone goes unturned, we make sure to look at smaller details like password policies, to make sure they aren't easily guessable by hackers. 

We'll let you know if there's anything to worry about in our reviews and will be contacting manufacturers to get issues fixed. Those with the riskiest security vulnerabilities will become Don't Buys. 

Should I buy it? 

We give each wi-fi router, wi-fi extender or mesh system a total test score, so you can see which are the best and worst.

In each review we summarise what we thought of the router or booster so that you can quickly get the information you need to decide which device is best for you and your needs.

84%The score a wi-fi router or mesh system needs to earn Best Buy status

The score for each router or extender is made up of a combination of the elements in the test. We don't take price into consideration – most routers supplied by your provider will be included for free as part of the broadband package.

The score is broken down as follows:

  • 90% performance
  • 10% ease of use

Although the score is broken down in the same way for wireless routers, wireless extenders and mesh systems, each type of device is evaluated in a slightly different way. This means the scores for each type of device are comparable within that category, but not across the three. 

A wi-fi router and mesh system needs to score 84% or more and an extender needs to score 74% or more in our tests to earn our Best Buy recommendation. Models that score 45% or less are labelled a Don't Buy as a warning to avoid them.


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