Troubleshooting Speed and Browsing Issues PDF Print

Why is my connection slow?

If you are experiencing a slow or degraded connection the first thing we will need you to do is complete a speed test.

We have an available bandwidth meter to check the bandwidth of your ADSL/ADSL2 connection; for Speed Faults the result in the black box of the test is required.

Click here to start conducting a speed test

Programs such as P2P, IM, email clients, or any other program that may use the Internet should all be closed when running a speed test as they will slow down your connection.

Please note that for 8Mbit plans Telstra will not look at a speed fault unless the connection speed is less that 1500 kbps.

The maximum speed of your connection may vary depending on your distance from a telephone exchange, line quality, the number of users in your area, or connection protocol overheads.

If the results of the first speed test do not reflect the speed of the plan you are ; then try completing a second test after doing the following:

  1. Power Cycle your Equipment - Switch off the ADSL modem. Unplug the power and phone cables from the back of the modem, and leave these cables disconnected for 20mins. This forces a reset of the software in the DSLAM at the phone exchange. Reconnect the cables, switch on the ADSL modem, wait for about 3 minutes, and then reboot your PC .
  2. Disabling your firewall - your firewall/security software may be blocking or slowing down traffic/ports on your computer
  3. Isolation Test - disconnect any device that plugs into the phone line in your house so that only your ADSL/ADSL2 modem is connected. Unfiltered alarm systems and Foxtel Digital installs can cause connection issues for your ADSL service.
  4. Second Modem - testing with a 2nd modem is advised, as it may be possible that your modem has become faulty or is overheating thus preventing or slowing down traffic flow.

I am able to access some websites/servers but not others?

If you are having trouble connecting to a secure site, or Yahoo, or MSN, or AOL, or you use VPN, and have severe performance problems, then you might need to tweak the MTU setting in your router. MTU or Maximum Transmission Unit is the largest packet a network device transmits.

Technical Overview

A packet sent to a device larger than its MTU is broken into pieces. Ideally, MTU would be set to the same — large — value on all your computers, routers and switches, as well as on all the parts of the Internet that you access. But you cannot control the MTU on the Internet, and in practice the optimum MTU size on your LAN is related to your hardware, software, wireless interference, etc.

  • Tweaking MTU size may work well in one situation, but cause performance and connection problems in others.
  • When network devices with different MTU settings communicate, packets are fragmented to accommodate the one with the smallest MTU.
  • Windows XP™ sets MTU automatically, that is, it optimizes computer MTU for you.
  • Once a network device fragments a packet, the data stays fragmented until arriving at the destination computer.
Changing the MTU

Setting MTU size is a process of trial-and-error: start with the maximum value of 1500, then reduce the size until the problem goes away. Using one of these values is likely to solve problems caused by MTU size:

  • 1500. The largest Ethernet packet size; it is also the default value. This is the typical setting for PPPoA, non-VPN connections
  • 1492. The size "recommended" for PPPoE (see below)
  • 1478 The optimal size for PPPoA
  • 1472. Maximum size to use for pinging (Bigger packets are fragmented.)
  • 1468. The size DHCP prefers
  • 1454 The optimal size for PPPoE
  • 1430. The size VPN and PPTP prefer
  • 576. Typical value to connect to dial-up ISPs

All DSL connections use ATM - it's built in to the protocol. PPPoE is less efficient than PPPoA because PPPoE is really PPP over Ethernet over ATM, and the extra layer wastes an extra 24 bytes protocol overhead in every packet.

For a PPPoA connection, if the speed is limited only by the modem speed, then an MTU value of 1478 is usually the best as this is the maximum value that avoids wasted padding bytes in the fixed size ATM cells that carry data over the link.

For the same reason, an MTU value of 1454 is usually best on a PPPoE connection. The optimum MTU for PPPoE is 24 bytes less (1478 - 24 = 1454) than that for PPPoA.

Note: If you change MTU on one computer, change it on your other computers, switches, and routers, as well.

Here is a site that takes you through setting your MTU with DOS ping http://www.dslreports.com/faq/5793/

I can't browse at all? What can I do?

If you are unable to go to any website like www.google.com.au the first thing you need to do. Is to check if you can browse by IP address.

For example try putting the following IP address into your web browser

202.60.73.170

Press the enter key, and an Apache page displaying the text "It works!" should display. If you see this page, then it means that the issue is to do with your DNS configuration. Here is how to manually fix it in Windows XP™ (similar steps can also be taken for other Windows Systems)

  1. Open up your Control Panel
  2. If you are not in Classic View click on Switch to Classic View in the upper left hand side of the screen
  3. Look for the Network Connections icon and double-click on it
  4. You should now see a Local Area Connection somewhere on your screen
  5. Right click on it and select Properties
  6. Select Internet Properties (TCP/IP) and click on Properties

    Local Area Connection Properties

  7. Select the Use the following DNS servers addresses: option and enter in our DNS servers
    Preferred DNS Server: 124.254.72.68
    Alternate DNS Server: 124.254.72.70

    Internet Protocol TCP/IP Properties

  8. Click on Ok
  9. Click on Ok again to close down the Local Area Connection Properties
  10. Now for the DNS Servers to be applied correctly to your computer do either of the following:
  11. Restart the Computer or right click on the Local Area Connection and select Repair

If you are still unable to browse it is either a firewall or connection issue. Try disabling your firewall/security software and see if you are able to browse. If not check out our Connection Troubleshooting guide.