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Hyper-V UDP broadcasts not getting out on virtual switch

    Question

  • Hi,

    I'm running Win10 in a Hyper-V VM on a Win10 host. I've set-up an 'external' virtual switch to allow the VM access to the local LAN. Within the VM I have an app that issues UDP broadcast messages that other devices on the LAN should pick up, however it seems they never get this UDP packet. When sent from the host OS it is fine. I've disabled firewall as well and tried setting MAC address spoofing, but to no avail. TCP traffic gets out to the LAN just fine.

    This is something that works fine on VMWare, so any clues how I can get it working in Hyper-V?

    Virtual switch settings:

    • External (connected to host PC's main NIC)
    • Allow management os to share this network adapter enabled
    • Under extensions, both filtering platform and NDIS capture are off.

    Thanks.

    Tuesday, November 3, 2015 7:11 AM

Answers

  • Hi Magra,

    I'm afraid I could not find any official documents about the issue.

    On the VM, perform a network capture to check if it is sending the UDP packets.

    Here is the link for Network Monitor:

    http://www.microsoft.com/en-us/download/details.aspx?id=4865

    Are you using network adapter or legacy network adapter? Try both of them to test.

    Best Regards,

    Leo


    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Wednesday, November 4, 2015 6:35 AM
    Moderator

All replies

  • Hi Magra,

    I'm afraid I could not find any official documents about the issue.

    On the VM, perform a network capture to check if it is sending the UDP packets.

    Here is the link for Network Monitor:

    http://www.microsoft.com/en-us/download/details.aspx?id=4865

    Are you using network adapter or legacy network adapter? Try both of them to test.

    Best Regards,

    Leo


    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Wednesday, November 4, 2015 6:35 AM
    Moderator
  • Hi there, did you ever resolve this? 

    Regards Niels

    Thursday, April 7, 2016 11:18 AM
  • Hi Leo

    I have basically the same issue, but could narrow it down a bit:

    Host-OS: Windows 10 (Fall Creators Update)

    Hardware: Microsoft Surface-Book, 16GB RAM, 1TB, using built-in WiFi and Surface USB Ethernet Dongle

    Virtual Switches on both network adapters, configured to be shared by Host-OS

    UDP-Broadcasts are not going out on Virtual Adapter on Surface USB Ethernet Dongle, but are going out on Virtual Adapter on built in WiFi.

    As soon as Surface USB Ethernet Dongle is de-selected from Virtual Switch (replace with something else, i.e. Internal Network), UDP-Broadcasts are going out and answered again.

    So, we suspect the Surface Ethernet driver to be the possible culprit.

    Confirmed on a HP Envy Deskside PC with same OS-Version, using built in Ethernet adapter as Hyper-V Virtual Switch, which works as expected.


    Roman Müller, Founder and CEO - Interware LLC

    Sunday, October 22, 2017 4:41 PM