Intermittent or slow broadband? Troubleshooting connection problems

by Chris Marling

Whether it's slow, intermittent, or not working at all, there are few things more frustrating than a dodgy broadband internet connection! 

Hopefully we can get your wayward web connection back on track. If you're having trouble with your mobile broadband connection, you should head over to our mobile broadband help and guides.

If you were looking to compare or buy broadband, see our home broadband and mobile broadband comparison pages.

Why is my broadband down or intermittent?

If your fixed-line broadband connection has gone down completely, or is intermittent, chances are you will need to contact your internet service provider (ISP) immediately. However, if your telephone landline is also down and you have it supplied separately by BT and not your ISP, it is well worth contacting the phone company first. If you're not sure of the technical support number or opening times of a particular company, you can check all of the major ones in our guide to customer and technical support.

Before you call them though, it's worth checking a couple of things. Firstly, is your hardware connected via the telephone master socket? Problems with internal wiring (or telephone extension cables) are a common reason for broadband internet and telephone faults, so be sure to test this: if you only have one telephone socket in the house, that's the master. 

If you have more than one, the master will be the one with a company logo on it (BT or Virgin Media, usually). If you are not connecting your internet connection directly through the master, do so now to test it - it may seem like a hassle, but it's important to check - for example, if you call out an engineer who then finds out it is a problem with your internal wiring and not the ISP, you may be liable to an expensive call out fee.

Secondly, if your phone line is working but your internet isn't, you may have a fault with your microfilter (pictured here and also known as a splitter), which is required for ADSL. If you have a spare, try to replace the one you're using and see if that solves the problem - you'll normally be sent at least two with your router. 

Also, it's worth fitting a microfilter to any phone extensions that are used (whether for burglar alarms, Sky boxes, etc) as these can cause problems even if the master socket has a microfilter. 

What can I do about slow broadband?

Many things can cause slow broadband; but you'll want to make sure there's actually a fault with your line before you call out engineers, as if they find it's your equipment at fault you can face hefty call-out charges.

If your broadband connection seems slow, you can test it first by using our free speedtest. We suggest you do series of tests, at different times of the day and on different days of the week (weekdays, weekends, etc). We also have a guide that explains broadband upload and download speeds in more detail.

If your broadband comes through a BT telephone line (so it's ADSL, ADSL2+ or fibre) you can check what maximum speed your line should be by visiting your provider's home page and finding the 'check what line speed I can get' box. This will let you put in your home phone number to be given an estimate of the speeds you should be getting. If you can't find it on their website, just give customer services a call.

Customers using Virgin Media should normally get close to the 'up to' speed advertised.

It is important that you see this speed as a maximum and not the speed you should expect to get on a regular basis. This is because a number of factors can affect your broadband speed...

Multiple machines
The speed you line is capable will be shared by all the machines in your home. If you are running three or four machines on the one connection at once, your speed could suffer significantly.

Multiple users
In the same way your connection is being shared around your home, once it leaves your house it is also being shared with your neighbours. This is one of the reasons why we suggest you do multiple speed tests: with most broadband packages, you can't expect to get the same speeds all of the time, as more people sharing at peak times means slower speeds. 

Wireless router
Using a wireless router can lead to slow broadband, compared to using a wired router. Before making a complaint, it is worth checking your connection through a wire if possible. Wireless routers can easily be connected via wires too, so this shouldn't be a problem as long as you can get your machine plugged in near enough to your router.

While Wi-Fi is both convenient and tidy, a drop in speed compared to wired is pretty much inevitable, and the further you get from the router the slower it will become.  

Old wireless modem/router
There are various classifications of wireless routers than can handle different speeds. If you have an older router, but have upgraded to a faster broadband service, your old wireless router may not be able to pump the signal through fast enough. 

As a rough guide, wireless-B can support around 5-6Mb, wireless-G around 20Mb and wireless-N around 100Mb. The latest 802.11ac standard claims to exceed 1Gb, though in reality will provide around 500Mb. 

You may be paying for a whiz-bang broadband connection, but it will still be reduced to the speed the weakest component you're using can cope with.

Traffic shaping
Also known as 'throttling', this is a broadband slowing method employed by a number of ISPs that affects certain types of traffic (often downloads). It can be done in two ways: either as a permanent part of the service or as a punishment for repeated heavy usage by customers. 

If your ISP only employs traffic shaping as a punishment, you may want to review whether you're downloading an excessive amount of data and discuss this directly with your ISP - it may be time to move to a different deal.

Read our guide to traffic management for more information.