Tutorials - ADSL > Trouble Shooting

Tutorials & FAQs: ADSL: Trouble Shooting

While ADSL is generally a reliable technology, problems do happen from time to time. This guide sets out to explain the most common faults and offers solutions as to how you can solve them as well as what you can do to speed up diagnosis for the support team. If you are currently experiencing a fault or think you might in the future, this guide is essential reading.

General Information

ADSL Faults Tend to balance equally between the following causes:

'End User' (you) Configuration error / Modem or Filter Fault.
BT Line Problem, Exchange Problem or outage within the BT ADSL Network (Called Collosus) - These can vary in impact between all UK ADSL customers, people just on your exchange or just your own line.
ISP (ie PlusNet) Problems - These tend to affect a lot of users at once

The first thing to do when looking at any sudden problem is work out if it is affecting everyone or just you. The graphs below show our current level of ADSL traffic in realtime (updated every 30 minutes) for each of the three residential product type. If there is a problem for any amount of our customers we would expect these graphs to reflect the lower bandwidth:

Broadband Pay As You Go

Broadband Premier

Broadband Plus

Click on the graph to be taken to more information about how this is generated, and to see the same thing for the last week.

You should note that if this graph ever "flatlines" (ie the line is flat!), it reflects either a reporting problem OR that we have reached a capacity bottleneck. We constantly upgrade as we grow and plan ahead to ensure this won't happen!

The best way to find out where a problem lies is to check Service Status and to ask other people. As well as posting in the forums, asking other users on the same exchange as you can often yield useful information.

Login Problems - Test Logins

A generic login exists that will work even if your account login refuses to work, or there are service problems. Also if you are experiencing intermittent problems with your connection, it's good to check with this test login, the login bypasses the Plus.Net systems totally.

Use the following details:

bt_test@startup_domain

(ignored)

Once authenticated, you can browse to a single site, http://www.bt.net/digitaldemo which currently consists of a single graphic image.

A second test login exists to show whether the connection between you and PlusNet is working. If you can connect to this, it proves that the BT ADSL network is working correctly and any connection problem lies within the PlusNet system itself, although we do see many cases where people have been originally trying the wrong username or their modem is sending the wrong password, so this should be double checked before logging a fault with support.

bt_test_user@plusdsl.net or @plus.net

(ignored)

To find out which username you should use click on the Connection Settings link to the left, and then navigate to 'Connection Details'.

There are no sites to visit using this login.

Synchronisation Problems

Synchronisation (synch), is the phrase used to describe the physical connection between your ADSL Modem and the DSLAM at the exchange. Synch should always happen when you have an active and working ADSL line and is not related to your actual ISP connection.

Synch is normally indicated by a solid green 'link' light (sometimes also called synch, ADSL, WAN, Internet or showtime).

If you don't have sync, you won't be able to login to any of the test logins as your connection is not active. Possible causes of a loss of Sync are:

An Exchange Fault
ADSL Not enabled yet
ADSL Ceased (Cancelled)
Faulty Line Splitter (AKA Micro Filter)
Faulty Modem / Router
Telephone line losing quality - Line noise, electronics on the line, or a short on the line

Support will log reported synch problems with BT (They cannot be caused by problems at the ISP side). Because BT charge £50 + VAT for a 'false' callout it is important that we rule out as much from the above list as possible.

If you are unable to get synch on your line, the following may assist in ruling out some of these items:

Ask other people who use your local exchange whether they have the same problem - This is not always conclusive as many exchanges have multiple DSLAMs, of which only one might have a problem.
Try the connection without splitters. See the ADSL Wiring and filters FAQ tutorial.
Try a different modem - This isn't always possible, but if you know anyone with ADSL, trying their equipment on your line is a very worthwhile test. Bear in mind that USB modems are notorious for losing sync intermittently, so if you have one, try a different type - This topic is covered further down the guide.

BT will often cease a line themselves if you change the details of your line. For example, changing the name of your line, unless it is due to marriage or divorce, will result in BT cancelling all line services. The only way to get your ADSL back in this case is to pay £50 + VAT and have the line activated again. You should ALWAYS check with BT and get confirmation in writing that your ADSL service will not be affected by any changes you plan to make to your BT Account.

Support should be able to advise further if the above still points towards a BT problem.

Disconnection Problems

People have a habit of reporting drops in Synch as being disconnected. It is important to differentiate the two. If you are losing Synchronisation on your modem or router, please refer to the section above.

If however your Synchronisation is remaining solid, but your ADSL (PPP Layer) connection to PlusNet seems to become disconnected, this is most likely related to one of the following:

ADSL Network / ISP Network Problems - Check the graph above and service status.
Internal Wiring Problems - make sure that you have tried the connection directly into the mastersocket with no extension leads and also make sure that you removed all other devices from the line when doing this (phones, faxes, sky etc).
Filters - Try with multiple splitters and also dig out an old 56K modem cable and try without splitters (but again make sure nothing else is plugged into the line when you do this).
Hardware - Make sure that you have re-installed the drivers to your modem to see if this resolves the issue. Also, if possible, try and borrow another modem from a friend and see if that works - or alternatively, take your modem to a friends and try to connect to their broadband account (it doesn't matter which ISP they are with).
BT Line problems - If you have checked all the above and still have an issue we can get BT to look into this further but if you do not confirm that everything has been checked BT will just send it back.
DNS problems (ie not getting disconnected, but unable to get to any sites)
Idle timeout, or "Disconnect when not in use" setting

When attempting to diagnose your fault, support will need to rule out all of the above in order to diagnose the problem. You should try to rule out as much as possible before contacting support about the problem.

Speed Problems

Important note:

You can check if your exchange is affected by engineering problems, plus see estimated dates for when the problems will be rectified, by checking for your exchange on the 'Exchange VP capacity check tool' page.

Again, speed problems can have a many causes:

Exchange Contention
Full throttle uploading
Unknown Spyware or a Virus
DoS against your IP
Faulty or over capacity Exchange
PlusNet's own Internet and ADSL 'central' bandwidth
Mis-configured user equipment

In order to quantify any speed problems, there are many speed checkers available for your use. Speed checkers provide an indication of the speed available on your connection. They are not always accurate, and results should be taken more than once at different times of the day to get clear results.

ADSLGuide Speed Checker

PlusNet Speed Checker

Connection Settings control panel

As a more reliable alternative to a speed tester, we recommend you spend 30 minutes downloading a file from http://www.mirror.ac.uk - This will display a more accurate download average than any speed checker. Similarly, you can upload a file to your webspace using FTP to test the upload speed of your connection.

On the BT ADSL (IPStream) products, we currently see our customers achieving the following kind of speeds at most times:

Again, before logging a fault with BT is important to rule out as much as possible from list above. Failure to do so may result in BT charging you £50 + VAT if the fault is found to be with your own setup. This would include closing any P2P clients you are running, rebooting your equipment, checking Service status and the forums for other people experiencing the same thing and ensuring that you are spyware / virus free by running suitable checkers.

Solving USB Modem Issues

There is a power management problem with some motherboards, including those using the Via KT7 chipset (which is found on several models of motherboard). This causes the USB ports to loose power at apparently random intervals. The symptoms would be that the Broadband ADSL will usually work fine for a short time and then the modem would just switch itself off or lose connection. After a reboot of the computer it will be OK again for a few minutes.

If you experience this problem we would recommend that you seek advice from your computer supplier or purchase an externally powered USB Hub.

You can also try downloading the latest 4 in 1 drivers from www.usbman.com, as this has been known to cure the problem.

Logging a Fault Procedure

In order to log a fault regarding your ADSL Connection, you need to follow the ADSL Fault Wizard on the 'Help assistant' section of the PlusNet portal. If you don't have access to the Internet for the duration of your fault, we can complete this over the phone.

To access the Wizard, visit Help assistant and select "Self-test and Raise a Fault" and then select "Self-test and Raise a Fault" from the Menu presented. Now follow the wizard through, choosing the relevant details in relation to your fault.

A ticket will subsequently be raised on your account, which will be used to handle your fault. You can view the progress of this at any time by following the route given above, but selecting "Check on progress of fault" at the second Menu.

Once your fault has been raised it will be assessed and one of three things will happen:

It will be returned to you, with a suggestion of measures to take or a request for additional information.
Your fault report will highlight a problem at our side, which will be fixed on the spot, or the fault will be escalated to our networks team for a resolution.
It will be logged with BT and escalated to our Faults department, who are specialists who specifically work with BT to resolve ADSL faults.

If your fault is logged with BT, you will be able to view the progress not just via the "Help assistant", but also via the BT.Com Fault tracker.

BT don't have a specific Service Level Agreement in relation to faults, however they do commit to responding initially to all reported faults (that is, reported by the ISP) within 48 hours.

Further Help

Other guides to solving common ADSL problems are available here on thinkbroadband or here.

Original Article by: ianwild - Edited by: MauriceB