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Fix BBR2 bugs on Windows 11

Anonymous
2025-05-08T10:11:45+00:00

Hello I have changed the congestion provider to BBR2 with the command

netsh int tcp set supplemental Template=Internet CongestionProvider=bbr2
netsh int tcp set supplemental Template=Datacenter CongestionProvider=bbr2
netsh int tcp set supplemental Template=Compat CongestionProvider=bbr2
netsh int tcp set supplemental Template=DatacenterCustom CongestionProvider=bbr2
netsh int tcp set supplemental Template=InternetCustom CongestionProvider=bbr2

I am running on Microsoft Windows [Version 10.0.26100.3915]

There appears to be multiple bugs, it breaks Steam as the Steamwebhelper fails to launch anymore, and when using Internet Download Manager it breaks all download hooking when changing back to CUBIC they work again, from what I can gather It breaks 'localhost' (the loopback interface) TCP traffic leading to slow or unresponsive connections within the same machine.

Best Regards.

Windows for home | Windows 11 | Internet and connectivity

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  1. Anonymous
    2025-06-15T15:16:15+00:00

    You have to execute these two commands in case connectivity is broken with BBR2:

    netsh int ipv6 set gl loopbacklargemtu=disable
netsh int ipv4 set gl loopbacklargemtu=disable
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  1. Anonymous
    2025-05-14T15:36:52+00:00

    Hello,

    Thanks for posting to Microsoft Community!

    I appreciate the detailed information you provided. However, it seems like you are currently using Windows 10, not Windows 11. To resolve the issues, you are experiencing with BBR2 congestion provider, I recommend upgrading to Windows 11 as it offers better compatibility and performance improvements. Once you have upgraded to Windows 11, you can try setting the congestion provider to BBR2 again.

    When everything is resolved, feel free to mark this thread as answer and helpful. Otherwise, please let me know if there's anything else I can help you with.

    Best Regards, Van Johnson | Microsoft Community Moderator

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  2. Anonymous
    2025-05-15T18:33:07+00:00

    Hello I am running Windows 11 that is the build number copied and pasted from command prompt, Afaik BBR2 is not supported on Windows 10 anyways it is only on 11.

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  3. Anonymous
    2025-05-21T23:33:55+00:00

    Can confirm, BBR2 is broken on windows 11 as of my latest update, many software will not work because of it, just on top of my head Steam wont work, and Listary wont work.

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  4. Anonymous
    2025-05-28T16:20:41+00:00

    I have spent an entire day and a system restore trying to figure out what was wrong with my computer. Steam and multiple other apps cannot open and... it's all because Windows messed up bbr2 somehow.

    Thank you so much for this post!!!! Switching back to ctcp fixed my issues immediately

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