Disable TCP Auto-Tuning to Solve Slow Network, Cannot Load Web Page or Download Email Problems in Vista

When Windows Vista is connected to high speed broadband Internet connection, there may be some incompatibilities and conflict problem or error such as the following:

  • Poor intermittent network performance.
  • Slow network loading.
  • Unable to open and load some websites or webpages using Internet Explorer or Firefox, where the blue loading bar keeps running for a long time, but the pages fail to load.
  • Java applets fail to download and open.
  • Cannot receive email or download from POP3 mail server by email clients such as Thunderbird. No mail arrived although users may see the message “receiving 1 of 3 messages”, and eventually the receiving process will time out with the error number 0×800CCC19 timeout.
  • Slow email sending or retrieval using Thunderbird and other clients.


The symptoms exist due to the new re-written TCP stack in Windows Vista that aims to take full advantage of hardware advances such as gigabit networking. Among the new feature in Windows Vista TCP/IP is Receive Window Auto-Tuning Level for TCP connections. TCP AutoTuning enables TCP window scaling by default and automatically tunes the TCP receive window size for each individual connection based on the bandwidth delay product (BDP) and the rate at which the application reads data from the connection, and no longer need to manually change TcpWindowSize registry key value which applies to all connection. Theoretically, with TCP auto-tuning, network connection throughput in Windows Vista should be improved for best performance and efficiency, without registry tweak or hack. However, this is not always the case, and may cause some Internet related issues and problems.

The workaround or solution to the above problem is to disable the TCP/IP AutoTuning in Windows Vista. Disabling auto tuning of TCP Windows Size should not cause any negative effects, only that TCP Window Size will always at default value without ability to optimization to each connection. Anyway, if there is any side effect after turn off auto tuning, simply re-enable back it.

Check the state or current setting of TCP Auto-Tuning

  1. Open elevated command prompt with administrator’s privileges.
  2. Type the following command and press Enter:

    netsh interface tcp show global

    The system will display the following text on screen, where you can check on the Auto-Tuning setting:

    Querying active state…

    TCP Global Parameters
    ———————————————-
    Receive-Side Scaling State : enabled
    Chimney Offload State : enabled
    Receive Window Auto-Tuning Level : normal
    Add-On Congestion Control Provider : none
    ECN Capability : disabled
    RFC 1323 Timestamps : disabled

Disable TCP Auto-Tuning

  1. Open elevated command prompt with administrator’s privileges.
  2. Type the following command and press Enter:

    netsh interface tcp set global autotuning=disabled

Enable TCP Auto-Tuning

  1. Open elevated command prompt with administrator’s privileges.
  2. Type the following command and press Enter:

    netsh interface tcp set global autotuning=normal

15 Responses to “Disable TCP Auto-Tuning to Solve Slow Network, Cannot Load Web Page or Download Email Problems in Vista”

  1. KO
    November 27th, 2009 11:18
    15

    After trying every solution on the web, here is the solution that I found really effective: Set your NIC’s duplex setting to “HALF” not FULL. Ex. If your on a 100mb network, set the problem machines to 100mb Half Duplex.

    Before running this fix, my WAN/LAN was 1.5 mb/s / 100 KB/s – horrible!
    After: 19/75 mb/s! A 13x/7500x fold increase!

    “Don’t care how/why it works, just that it works!”

  2. KnightKat
    September 23rd, 2009 23:05
    14

    I disabled this because I read that it would fix a problem I’m having. It didn’t help and now when I try to turn it back on it says “Set global command failed on WSH The system cannot find the filed specified” Can anyone help me?

  3. Johnson
    June 4th, 2009 10:07
    13

    Thanks, the tutorial is easy to follow. The web seems slightly faster. I still need to test it more.

  4. Download Vista tcpip.sys and UAC Auto Patcher to Increase TCP Connection Limit » My Digital Life
    July 12th, 2008 10:22
    12

    [...] Vista TCP Auto Tuning feature to minimize possible networking [...]

  5. Matt
    May 23rd, 2008 16:38
    11

    I could access every website on the internet except one (www.telemarket.fr) from one computer on my network. All the others could access it fine with the same IC. This worked like a charm and now I can access it.

  6. sometimes
    March 23rd, 2008 00:18
    10

    This patch is useless with Vista SP1 and this “Safe Mode black screen” at each startup, because the tcpip.sys is not signed. (On 64bit and after SP1 on 32bit Vista too)

  7. Outlook 2007 Slow While Downloading POP3 Email » My Digital Life
    September 6th, 2007 23:21
    9

    [...] To solve the problem, simply disable the Vista AutoTuning function which is the most common suggestion and fix for various network problems in Vista. [...]

  8. Increase Multithread Download Speed by Disable Vista Auto Tuning on TCP/IP » My Digital Life
    May 24th, 2007 23:03
    8

    [...] better performance for network downloading and web surfing. Other than the problems mentioned previously, Auto Tuning may also cause reduce the rate of establishing network connection, especially when [...]

  9. Optimaliser Vista for BitTorrent, eMule, P2PTV
    April 17th, 2007 03:23
    7

    [...] av TCP/IP Auto-Tuning ved å kjøre følgende kommando i kommandolinjen: netsh int tcp set global [...]

  10. Optimize Vista for BitTorrent, eMule, P2PTV | TorrentFreak
    April 10th, 2007 01:06
    6

    [...] Disable the TCP/IP Auto-Tuning feature by running the following command in command [...]

  11. Windows Vista tcpip.sys Connection Limit Patch for Event ID 4226 » My Digital Life
    April 9th, 2007 03:31
    5

    [...] the TCP/IP Auto-Tuning feature by running the following command in command [...]

  12. Mark
    March 29th, 2007 02:02
    4

    It fixed my problem with email after updating to vista from xp. Email would not dl but 1 message and timeout.

  13. Nell
    March 28th, 2007 07:23
    3

    I tried this because I was experiencing just these issues with Vista, but it didn’t help. Thanks for trying to help, though…

  14. Seite kann nicht angezeigt werden / kein Mailabruf / langsames Netzwerk - Dr. Vista - Windows-Hilfe mit Rezept
    March 23rd, 2007 22:45
    2

    [...] Namen "Autom. Abstimmungsgrad Empfangsfenster". ( sinngemäße deutsche Übersetzung dieses Artikels – vielen Dank an Autor.) __________________ Vista Update Pack 1.0 – Empfehlungs-Wettbewerb – [...]

  15. Jug
    March 22nd, 2007 16:17
    1

    Only do this if you experience problems though, because if your hardware supports these techniques properly, it’s likely Vista will otherwise give improved networking performance compared to XP with this enabled. So it should be considered just a fallback solution.

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