Many users reported that their internet speed has dropped down since the release of Windows 10 Anniversary Update. If your internet speed was fine up until the upgrade to Windows 10 Anniversary Update, the following could be the reason why it happens.
First introduced in Vista, Window Auto-Tuning is a feature that improves performance for applications that receive TCP data over a network and is part of any newer Windows system, including Windows 10. It’s enabled by default in the system but is disabled for applications that use the WinHTTP (Windows HTTP Services), such as RDP, File Explorer, and Windows Update, or WinINET (Windows Internet), such as Outlook, Internet Explorer, etc.
While the intention of having this feature enabled is to improve the performance for receiving TCP data, it does need your other network equipment, router, firewall, etc.kick in, stay current to comply with the RFC 1323 standard. If not, it could sometimes cause slow data transfer or a loss of connectivity.
To check if Windows Auto-Tuning is enabled in the system, run the following command in the Command Prompt window.
netsh interface tcp show global
If you see the Auto-Tuning level is disabled, you need to investigate the issue further as this feature has nothing to do with the slowness. However, if you do see it is set to Normal, like the screenshot above, it could be the reason behind the slowness after the upgrade.
Now, let’s disable it by running the following command and see if it helps.
netsh interface tcp set global autotuninglevel=disabled
You will need to restart the computer to have the change to take effect.
Once disabled, don’t forget to run some tests to see if the speed improves to the level before the upgrade. If not, it’s recommended that you turn the feature back on again by running the following command.
netsh interface tcp set global autotuninglevel=normal