Troubleshoot your PC

Networking devices, such as SPI firewalls, some NAT routers, VPN endpoints, Wi-Fi devices have problems with the way Windows Vista resizes the TCP Window. Try the tweak only for Vista computers.

Networking devices, such as SPI firewalls, some NAT routers, VPN endpoints, Wi-Fi devices have problems with the way Windows Vista resizes the TCP Window. Possible symptoms include: web traffic ok, email timeouts on receiving only, slow or no network file server access, random network timeouts or connectivity problems, freezing or slow web browsing or VPN connections. This issue can be fixed by disabling TCP/IP autotuning.

Disabling TCP Window autotuning limits the TCP Window to 65535, which may not be adequate for faster broadband internet connections. So try the step, restart the computer and check if this worked. If not, enable it back again.

Click on start  type cmd  right click on “cmd.exe” to “run as administrator”.In command prompt type

• regsvr32 actxprxy.dll
• netsh interface tcp set global autotuning=disabled

• netsh interface tcp set global autotuninglevel=highlyrestricted

• netsh interface tcp set global autotuning=normal