RWIN / TCP Window Size Problem


I have a problem with Windows Vista Ultimate x64 - Anytime I try downloading anything through IE, Opera and FireFox I only get a download speed of some 30-50 kB, even though I have a 5mbit ADSL connection.

Now, I also tried testing my download speed on torrents and with download managers, and when I use these I get my full download speed (~500 kB) - this is because when I download through torrents or download managers, I have multiple connections to the file so I can get the full speed.

So the problem is that I have some strange download speed limit per connection (and browsers use only one connection when downloading files). I'm guessing the Vista auto tune feature isn't changing my RWIN or TCP Window Size, so I need a way to somehow manualy change this.

I also tried turning the auto tuning to restricted and disabled, but it didn't help. Also, when I set it to experimental, I have no internet at all.

P.S. I'm using the integerated network adapter of my Intel DP35DP motherboard.


Hi SeW800,

Let's try a few things here.  First, check Intel website and make sure all driver for the motherboard and BIOS are up to date. 

Disclaimer:  Modifying BIOS/ complementary metal oxide semiconductor (CMOS) settings incorrectly can cause serious problems that may prevent your computer from booting properly. Microsoft cannot guarantee that any problems resulting from the configuring of BIOS/CMOS settings can e solved. Modifications of the settings are at your own risk.

Once everything is up to date, you might want to try enable and disable these settings to see if it will work better:

Vista Congestion Provider - For TCP connections with a large receive window size and a large bandwidth-delay product, Compound TCP (CTCP) in the Next Generation TCP/IP stack aggressively increases the amount of data sent at a time by monitoring the bandwidth-delay product, delay variations, and packet losses. CTCP also ensures that its behavior does not negatively impact other TCP connections. In testing performed internally at Microsoft, large file backup times were reduced by almost half for a 1 Gigabit per second connection with a 50 millisecond round-trip time. Connections with a larger bandwidth-delay product can have even better performance.

Enable - netsh interface tcp set global congestionprovider=ctcp
Disable - netsh interface tcp set global congestionprovider=none

netsh interface tcp set global ecncapability=enabled/disable
netsh interface tcp set global congestionprovider=ctcp/none
netsh interface tcp set global rss=enabled/disable
netsh interface tcp set global autotuninglevel=normal
netsh interface tcp set global chimney=enabled/disable



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Question Info

Last updated February 14, 2019 Views 21,742 Applies to: