UK centric broadband information and diagnostic help.

Have you turned it off and on again?

Only kidding… but seriously.. ISP telephone support will likely have you do that.. 

One of the major gripes users have is the “speed” of their broadband. In the UK there are three main ways of getting broadband. The OpenReach maintained network, the Virgin Media (Liberty Global) network and also via Mobile operators who offer a 4G based solution. There are other various providers outside of these but they are usually more limited in availability, a good example being:

My main focus here will relate to the OpenReach based networks but I’ve had Virgin Media cable in recent years also, so will allude to any interesting differences. 

Generally speaking, when your looking at a speed issue, like most problems, it’s a process of elimination and understanding of the problem. 

Firstly there is a difference between the connection physically and logically to your ISP. 


This is the speed at which your modem (which might be built into your router) can connect to the equipment in the telephone exchange (Central Office for our American friends) or green box in the street (aka PCP). The determined synchronisation speed on the connection will be the maximum at which data can pass down the line and shouldn’t vary too much on each reboot of your modem / router. If it does then there is likely a problem or the ISPs dynamic line management (DLM) is trying to deal with the said problem or repeat reconnections. 

Things that can effect the sync connection rate are:

  • Attenuation – how far from the other end. 
  •  REIN – Repetitive Electrical Impulse Noise.
  • SHINE, – Single High-level Impulse Noise Event.
  • Extension wiring – further attenuation and susceptibility to further electric noise. 
  • Equipment issues – faults happen. 
  • Bridge taps – legacy telephone wiring. 
  • Poor cable shielding – causing some of the above. 
  • Engineer mistakes – Sky TV splitters in before the microfilters is a common one.
  • Capped profile settings by the ISPs DLM (whether intentional or not).
  • So all of the above might be good to the modem, now check to the device!

To check your sync rate as a customer, this will involve logging onto your home router (Seek ISP support or router support for instructions). Generally there is a status page on the interface that will give you the connection details such as sync rate downstream and upstream, uptime, and maybe more.  If this looks like to what was estimated when you had the service provisioned then all is good. 


The next “speed” we’re interested in is the throughput. A good metaphor for this would be a water pipe. If the sync mentioned above is the pipe its self, throughput is the water going through it. For the sake of the metaphor, the pressure is a constant in the water pipe! 

This is tricky to diagnose as as the issue can lie on the customers side as much as is can with the ISP or beyond depending on the endpoints of the testing and everything inbetween.

Various things that can effect this:

  • Fault with the sync speed – knock on effect.
  • The server being tested to not providing you with data fast enough.
  • Congestion on a network – not necessarily the ISP’s, could be beyond them.
  • Downloading on your connection while running speedtests – congesting your part of the network to give you slower, skewed results.
  • Connection to the router such as via wireless 

Generally an ISP, whether is OpenReach based or Virgin Media is eventually going to have you down to the bare minimum; a single PC, via a ethernet cable directly into the router, potentially with the WiFi disabled on the router (or they’ll be checking for other devices connected at the time of testing). Even then there are various checks as mentioned above; sync rate, ethernet rate, errors in the passing traffic, test locations for speed testers and so on.

By now though, the ISP should be close to narrowing down if the problem is on their side or on yours. It could be that your wireless was being strangled by too many other devices or that there were so many other noisy networks in close proximity. Then again it could be that your ISP has overwhelming demand in a particular exchange/area and can’t meet the bandwidth demands at peak times.. These things happen but it’s important to come to logical conclusions so they can be tackled. I..e ISPs have capacity planning teams and although they do their best to stay ahead of demand, it can sometimes outstrip supply. 

Testing throughput:

Here are some throughput speedtesters:

Netflix speed tester:

Misc / Some sockets:

Two sockets shown here: One is a old telewest phone socket on the right and the left is a old BT (OpenReach) socket. Both have the front covers removed to show their test sockets which are inside of the right. Not a great picture but you can see the BT one has a microfilter plugged straight into it. With a silverish cable going out of shot to the router. In the lower half of the picture, we see a splitter with two cables coming out. These are going off to Sky set-top boxes. Often as a support engineer, I would see this plugged in first and then the filter coming off of it. That would cause no end of problems as the microfilter needs to be the first device out of the socket to separate the phone frequencies from the broadband ones. Faxes and standard telephone splitters were other common offenders for this issue as well as unfiltered extensions that were in use. 


Connection Monitoring:

Below is a ping monitor to my router. You either need a static IP (doesn’t change when your broadband connection drops and reconnects as most use dynamic IPs) or a dynamic DNS provider thats setup on your router (support required) so you can always connect back to it if the connection does drop and reconnect with a new IP. Such a provider is Essentially that IP address is your public address on the internet and without it, you can’t keep an eye on your connection being up as you don’t have an awareness of where that is without the above. 


My Broadband Ping - Sky FTTC 80/20

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