Tweaking Your Wireless Network in Windows Vista
If you're experiencing a slow connection over your wireless home network on a Windows Vista computer, it may because you're trying to connect to an older router. In Windows Vista, Internet Protocol version 6 (IPv6) is enabled by default, but some older wireless routers don't support this protocol. If your router doesn't support IPv6, you may need to disable it and use IPv4 instead. Check your router's documentation to see which protocol it uses, or run Microsoft's Internet Connectivity Evaluation tool to determine your router's IPv6 support.
To disable IPv6, start Windows Vista, then click the Start button and select Network. Select Network and Sharing Center and Manage Network Connections. Right-click the item marked Wireless Network Connection and select Properties. Uncheck the box beside IPv6. Click OK and reboot your computer.
Windows Vista's autotuning can also cause problems with your Internet connection. To turn it off, click the Start button and type cmd. Right-click the cmd entry, which appears under Programs, and select Run as administrator. At the command prompt, type netsh interface tcp set global autotuninglevel=disabled and press Enter.
Use these methods whenever you're having a problem with the Internet speeds on your Windows Vista computer. Be sure to make a note of every change you make to your system settings so that you can undo the changes should they cause problems. If you experience difficulties you can't solve on your own, visit the Microsoft Help and Support website.