Troubleshooting: Slow Speeds (Zen 8000 services)
Aim of this Article:
The aim of this article is to provide troubleshooting advice for customers experiencing slow connection speeds on their Zen 8000 ADSL Broadband service. Before conducting these diagnostics we advise restarting your computer and Broadband equipment to eliminate the possibility of a temporary issue affecting your connection.
Please note: if your service has been activated for three days or less you are likely to experience download speeds no greater than 2Mbit/s (2000Kbit/s or 250KB/s).
Step 1:
Perform a speed test using BT’s speed test utility. A guide to using, and understanding, these tests can be found here:
Using the BT speed tester
Before testing you should restart your computer and ensure all other computers on your network are shut down. Any software on your computer which uses the Internet must be closed (games, peer-to-peer software, messenger programmes and Web pages).
Once the test is complete you will receive the following information:
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IP profile of your line
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DSL Connection rate
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Actual speed throughput
Your IP profile is configured based on your DSL Connection rate. The following Knowledge Base article provides details of which IP profile should be assigned based on the DSL Connection rate:
IP profile table
If the IP profile is not correct proceed to Step 2.
If the IP profile is correct then the ‘Actual speed throughput’ should be within the range illustrated in the following Knowledge Base article:
ADSL Performance Thresholds
If the 'Actual speed throughput' is below the threshold proceed to Step 3. The diagnostics in Step 3 may also help improve speeds even if the Actual speed throughput result is within the correct threshold range.
NOTE: The BT performance tester may only be used once every three hours.
Step 2:
Ensure your equipment is set up as illustrated in our setup guide*1.
Click here to view the setup guide.
Once you have set up your equipment as per our guide it may take up to three days for your connection speeds to improve. Use the BT speed tester to determine whether your IP profile has been set correctly for your DSL connection rate.
If you are see no improvement in the IP profile and IP profile you should repeat this test from the BT Test socket. The following guide illustrates how to test from the BT Test socket:
How to test from the BT Test socket
NOTE:
*1 - This step should be carried out even if the service has worked in a different configuration previously. Best performance and reliability is gained by connecting to the BT master socket and ensuring telephone devices on extension sockets are correctly filtered.
Step 3:
If you are using a cable to connect your computer to your Broadband ADSL router proceed to Step 4.
If you are using a Wireless connection between your computer and your Broadband ADSL router please perform the following checks:
If the speed is still low on the BT speed test proceed to Step 4.
Step 4:
There may be software running without your knowledge that is using the Internet connection and causing slow speeds. The following diagnostics should help determine if this is the case:
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Install anti-virus and firewall software and perform a full system scan. If you already have anti-virus software ensure it is up-to-date before performing a scan.
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Check for adware/spyware using an anti-adware/spyware programme.
If the anti-virus and anti-adware/spyware do not find any results please proceed to Step 5.
If virus or adware/spyware software is found follow your anti-virus or anti-adware/spyware’s advice for removal. Once removed conduct another full system scan to verify the virus or adware/spyware has been removed. Once verified conduct another BT speed test. If the problem continues please proceed to Step 5.
Step 5:
Modify the MTU of your computer to 1458 or 1430 and test again. Instructions, and a tool, for doing this may be found here:
MTU Tools
If speeds continue to be below the thresholds please contact Technical Support for further advice. When contacting Support you should provide details of the speeds observed, as shown by the BT speed test.
If speeds are within the published thresholds please see the following Knowledge Base article for an explanation of why this is the case:
Contention Information
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