Common ADSL diagnostics

Sometimes ADSL lines can go wrong, and we’ll do the best we can help to help out. Often it is a fault with BT’s network but we require customers to perform certain checks before reporting the fault to BT.

Here are various common scenarios and some checks to make. You may want to print this page out when you take out a new connection with us!

It works over a cable, but not through wireless

Symptoms: Your connection works fine via if you connect your computer through a cable, but it is intermittent when connecting through wireless.

This is not typically an ADSL fault which we can help with. You will need to relocate your wireless router, buy a bigger aerial for it or invest in a repeater if you have a large premises – we would advise contacting Solwise for some friendly purchasing advice.

“No synchronisation” faults

Symptoms: Your router’s ‘ADSL’ light flashes rather than being on constantly (they typically flash while they are trying to connect). Alternatively the router connects and disconnects

The most important question is what’s changed? Have you done anything to your phone line that might have precipitated a problem, examples include:

fitting another telephone extension, even just changing a telephone on an existing one?
moving a router or re-cabling internally?
a visit from a Sky+ engineer?

Note that you must either have an ADSL microfilter fitted on every extension on your premises, or make sure every extension is run from the phone socket of the splitter in your master socket. If any devices are connected unfiltered to your telephone sockets, you may encounter problems with your ADSL line synchronising.

The most important thing you can do to rule out your premises wiring is to disconnect every other telephone device from your wiring, and to connect only your ADSL router, and to make sure it is connected to the master socket in your house.

“Authentication failure” faults

Symptoms: the router will typically report an authentication failure in its logs.

This can often happen as a result of BT mis-wiring something at the exchange, but obviously if you have just reconfigured your router and are not sure of your expected username and password, contact support to ask what it should be.

Please also check your typing very carefully and make sure you are not confusing capitals with small letters or Is with 1s.

Stuck in first gear

Symptoms: you have a working connection, but with very low throughput and slow downloads.

Firstly, we must assume that you are the only user of your connection. Do not leave your wireless connection unsecured, and be sure that you know your computers aren’t infected with any virus, as either is likely to result in your connection being choked. You can spot there might be a problem if your router’s “traffic” light is blinking quickly, when you think you’re not using the connection.

When trying to diagnose this kind of fault you should look at your ADSL sync speed. Your router will generally advertise this through its control panel.

Unfortunately BT typically guarantee a sync speed of about 1-2Mb for a Max line, despite the technology being capable of up to 8Mb. So if your connection runs any faster than this, there may be no cause for complaint.

You may be able to improve your synchronisation speed by following some of the steps under “No sync” faults above, i.e. disconnecting other extensions, making sure microfilters are fitted and so on.

However if your synchronisation speed is high, and you’re consistently not getting throughput that is near it, please contact support for advice.