Troubleshooting Vista connectivity issues

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Troubleshooting Vista connectivity issues with a firewall

Symptoms: When you try to use a Windows Vista computer behind a firewall device, you may experience some network connectivity issues as below.

Programs may respond slowly.
Programs may stop responding.
Slow file transfers
Slow Internet connection or doesn’t connect to the Internet.
Access to local file servers is extremely slow and sometimes it may not work.

Cause and Solution: By default, the Receive Window Auto-Tuning feature in Windows Vista uses a Window Scaling factor of 8 for non-HTTP connections. If you try to make an non-HTTP connection, this issue does not occur. To work around this issue, determine whether Windows Scaling is being handled incorrectly by the firewall device. To do this, follow these steps:

1.	Click Start, click All Programs, click Accessories, and then click Command Prompt.
2.	At the command prompt, type the following command, and then press ENTER: netsh interface tcp set global autotuninglevel=disabled This command disables the Receive Window Auto-Tuning feature.
3.	Try to make a non-HTTP network connection. Note If the connectivity problem is resolved, contact the manufacturer of the firewall device for steps to correct the issue.
4.	At a command prompt, type the following command, and then press ENTER: netsh interface tcp set global autotuninglevel=normal This command enables Receive Window Auto-Tuning again so that you can take advantage of the network throughput performance increase it provides

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