Windows 10 Anniversary Update, the major feature update for Windows 10, comes with a feature called TCP/IP Receive Window Auto-Tuning which is enabled by default. This feature is intended to improve performance of apps which receive TCP packets over a network. Under certain conditions, this feature can reduce your Internet speed. Here is how to check if you are affected by this issue and fix it if required.
The Receive Window Auto-Tuning feature was introduced in Windows Vista. There, it was not enabled by default. In Windows 10 Anniversary Update, it is enabled out of the box to manage your network transfer data. While it should serve most of users well, in some cases it can reduce your network performance.
To check out the state of Receive Window Auto-Tuning, you can do the following.
- Open an elevated command prompt.
- Type or paste the following command:
netsh interface tcp show global
- In the command output, look for the line "Receive Window Auto-Tuning Level". If its value says "normal", this means the feature is enabled. If your Internet speed is notably slow, then you can try to disable it.
- To disable Receive Window Auto-Tuning, type the following command:
netsh int tcp set global autotuninglevel=disabled
After that, test your Internet speed. If you were affected by the incorrect behavior of the feature, you should get improved network performance (thanks Martin).
- If your network performance does not change or becomes worse, you can re-enable Receive Window Auto-Tuning by typing the following command:
netsh int tcp set global autotuninglevel=normal
That's it. In comments, tell us if you got your Internet speed improved by changing the mentioned option or it has no effect in your setup?