Summary: How to troubleshoot slow broadband speed problems.

Want to report a problem with your broadband speed? Use our Broadband Troubleshooter.

Before you do, we recommend following the troubleshooting advice on this page. You might be able to fix the problem yourself.

Once the problem is fixed, be sure to follow our tips for the best broadband speed to keep things running smoothly.

Before you start troubleshooting, find out how fast your line can go

There's no point in troubleshooting if you're already getting the fastest speed your line can support. Before doing anything else, go to the BT Availability checker and enter your telephone number.

You'll see which exchange you're on and an estimate of the speed your line can support. If you're getting speeds close to the estimate, there's nothing we can do as your line is going as fast as it can. See our Broadband speed - the basics guide to find out how this works.

Now you know how fast your line can go, find out where the problem is

Run a BT Speedtest (see our BT Speedtest guide if you need help). The results will show your current speed and how your line is profiled.

In order of importance, the figures you should look for are:

  1. DSL Connection Rate (DOWNSTREAM) - this measures the speed of the connection between your property and the exchange, in normal conditions it should be close to the figure reported by the BT Availability Checker
  2. IP Profile - this is the fastest speed you can currently get whilst also receiving a stable connection. Normally this will be just under your DSL Connection rate
  3. Download Speed - the actual speed you're downloading at. In normal conditions this will be close to but never higher than the current IP Profile

After running the BT Speedtest, which of the following problems do you have?

Click on the type of problem you're having and we'll show you what to do.

What to do if your Downstream Rate is too low

On a stable line the Downstream Rate should be close to the maximum speed reported by the BT Availability Checker. In the event of a problem, the Downstream Rate will reduce to try and keep your broadband stable.

If you want to report a problem, use the Broadband Troubleshooter, but we recommend following the advice below first, you might be able to fix it yourself.

Make sure your telephone line is working

You'll see problems with your broadband if the telephone line isn't working properly. Pick up a telephone handset and check for a dial tone:

  • If the line is noisy or you can't hear a dial tone: Report the problem to your telephone provider (if that's us, go to the Telephone troubleshooting guide)
  • If the line sounds clear and I can hear a dial tone: Check that your Microfilters are fitted correctly

Check that your Microfilters are fitted correctly

Broadband shares the line with your telephone service. Microfilters separate the signals and prevent one from interfering with the other. Subsequently, anything connected to your line needs to pass through a microfilter. If you need help with this, our Fitting microfilters guide will show you how to set them up properly.

If your microfilters are fitted correctly and your downstream rate is still low, connect your broadband to the master socket.

Connect your broadband to the master socket

You should find the master socket close to the point where the telephone line enters your property. If don't know what it should look like, please see our BT master socket guide.

Unplug everything from your line (including set-top boxes, other telephones and all microfilters) and connect your router to the master socket through one microfilter.

  • If the downstream rate increases: Either your extension wiring or something connected to your line is causing the problem. Find out which by checking after plugging each piece of equipment back in. Try replacing your microfilter(s) if you can't find the culprit
  • If the downstream rate remains low: Try a different router

Try a different router

If you can, try a different router or modem on your line.

  • If the downstream rate increases: Your current router is faulty and needs replacing, if you got it from us in the last 12 months, contact us for a free replacement
  • If the downstream rate remains low: Your current router is fine, please report the problem to our Support Team
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What to do if your IP Profile is too low

The IP Profile dictates the maximum speed you can download at, it's set at your telephone exchange and will vary according to the condition of your line. In the event of a problem, the downstream rate will be reduced to try and improve stability. When this happens the IP Profile will quickly reduce to match. It will only rise if the line remains connected at a higher downstream rate for up to 3 days.

Bearing the above in mind, if your IP profile is considerably lower than your downstream rate, the problem will fix itself if your connection is stable.

If the problem isn't fixed after 3 days, your connection is probably dropping. Try troubleshooting for a dropping connection or report the problem using the Broadband Troubleshooter.

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What to do if your Download Speed is too low

In ideal conditions the download speed will be just under the IP Profile. If there's a considerable difference and you want to report a problem, use the Broadband Troubleshooter, but we recommend following the advice below first, you might be able to fix it yourself.

Check our Service Status posts

If there are problems on our side of the network, we'll post about them on Service Status. If a speed affecting problem is open, your speed should improve once it's closed.

Scan your computer for viruses and spyware

Viruses and Spyware can slow down your computer and subsequently your download speeds. There are a number of programs (such as Plusnet Protect) which can help you find and remove these from your system. Run a full virus scan to make sure your computer is ok.

Using Wireless? Make sure it's working properly

If you're using a wireless network, try connecting with an Ethernet cable. If this improves your speed you should consider changing the position of your router/computers and the channel that your wireless network broadcasts on. See our Wireless signal guide for more help with this.

If you can, try a different router or modem on your line. If this fixes the problem, your hardware is faulty and needs replacing (if you got it from us in the last 12 months, contact us for a free replacement).

Is there a problem at your telephone exchange?

Problems at your telephone exchange can affect your broadband speeds. Put your number in the Usertools Exchange Checker to find the current status of your exchange. If the VP (Virtual Paths) status is 'Red' then you might see slower speeds, particularly at peak times. If this is the case, BT will already be aware of the problem and they'll be planning to expand the exchange capacity to fix the problem.

If you've followed all the advice here and your speeds are still low, please use the Broadband Troubleshooter to report the problem

This page last updated 20th May 2011