If you’re affected by this issue then you should have read this post. Microsoft posted a KB article for when virtual machines lose network connectivity when you use Broadcom NetXtreme 1-gigabit network adapters on Windows Server 2012 Hyper-V or Windows Server 2012 R2 Hyper-V.


When you have Hyper-V running on Microsoft Windows Server 2012 or Windows Server 2012 R2 together with Broadcom NetXtreme 1-gigabit network adapters (but not NetXtreme II network adapters), you may notice one or more of the following symptoms:

  • Virtual machines may randomly lose network connectivity. The network adapter seems to be working in the virtual machine. However, you cannot ping or access network resources from the virtual machine. Restarting the virtual machine does not resolve the issue.
  • You cannot ping or connect to a virtual machine from a remote computer.

These symptoms may occur on some or all virtual machines on the server that is running Hyper-V. Restarting the server immediately resolves network connectivity to all the virtual machines.


This is a known issue with Broadcom NetXtreme 1-gigabit network adapters that use the b57nd60a.sys driver when VMQ is enabled on the network adapter. (By default, VMQ is enabled.)

The latest versions of the driver are 16.2 and 16.4, depending on which OEM version that you are using or whether you are using the Broadcom driver version. Broadcom designates these driver versions as 57xx-based chipsets. They include 5714, 5715, 5717, 5718, 5719, 5720, 5721, 5722, 5723, and 5780.

These drivers are also sold under different model numbers by some server OEMs. HP sells these drivers under model numbers NC1xx, NC3xx, and NC7xx.


Broadcom is aware of this issue and will release a driver update to resolve the issue. In the meantime, you can work around the issue by disabling VMQ on each affected Broadcom network adapter by using the Set-NetAdapterVmq Windows PowerShell command. For example, if you have a dual-port network adapter, and if the ports are named NIC 1 and NIC 2 in Windows, you would disable VMQ on each adapter by using the following commands:

Set-NetAdapterVmq -Name “NIC 1″ -Enabled $False
Set-NetAdapterVmq -Name “NIC 2″ -Enabled $False

You can confirm that VMQ is disabled on the correct network adapters by using the Get-NetAdapterVmq Windows PowerShell command.

Note By default, VMQ is disabled on the Hyper-V virtual switch for virtual machines that are using 1-gigabit network adapters. VMQ is enabled on a Hyper-V virtual switch only when the system is using 10-gigabit or faster network adapters. This means that by disabling VMQ on the Broadcom network adapter, you are not losing network performance or any other benefits because this is the default. However, you have to work around the driver issue.

Get-NetAdapterVmqQueue shows the virtual machine queues (VMQs) that are allocated on network adapters. You will not see any virtual machine queues that are allocated to 1-gigabit network adapters by default.

Sigh. I hope Broadcom are quicker about releasing a fix than Emulex (customers are waiting 10 or 11 months now?).

34 comments so far

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  1. Hi Aidan, I have a 3 node Hyper-V cluster up on WS2012 with only Intel 1 gigabit adapters. Here’s Get-NetAdapterVmq output from one of the nodes – http://1drv.ms/1kiEMuG and VMQ is enabled. Fortunately I’m not having any issues described above with Broadcom adatpers, but I’m curious why is that :-)


    • That’s the nature of these things. Lots of variables and failure is not guaranteed.

  2. Broadcom Network adapters have historically been hit or miss. At my work, ESXi boxes have had issues with them, we have had Windows 2008 R2 SQL/Exchange servers that have issues and all those issues would clear up when replaced with Intel/Cisco cards.

    We finally got to point where we just order Intel cards in all new Dell boxes and call it a day.

  3. FYI We’re experiencing similar symptoms but with 10Gb Broadcom adapters and some of our VMs. It seems that older OS i.e. 2008 R2 and prior are affected. Restarting the guest OS doesn’t resolve anything but switching the network adapter to DHCP then set back again its static IP resolves the issue for us for some odd reason. Looks like something wonky is happening in the integration services/drivers for the vNIC.

    We haven’t tried disabling VMQ yet on the physical adapters. Maybe something to explore.

  4. That would explain a lot… I had that issue a few times with my NICs integrated in Dell R420 :/ I’ve had them in a team in WS2012R2 cluster node and I would loose all network connectivity to all VMs and the node. Though I did not need to reboot the server – in my case I had NICs in team as active-backup and I just needed to change active NIC to restore connectivity (logged in with idrac :) ). I see it’s a good thing we switched to Intel NICs.

    btw. I had another NIC in server for cluster only network and I wondered why that was working…

  5. We are currently experiencing this issue and I was going to disable VMQ this weekend.

    Do you know if the command needs to be run on the NIC team or just the NIC’s that are members of the team?

    Any advice appreciated.

    • Disable it in the advanced settings of the pNICs.

      • Hi Aidan

        Thanks for taking the time to reply I successfully disabled VMQ on the NIC’s.

        So far no loss of connectivity so fingers crossed!

        Again thanks for replying :)

        • Still no drop outs which is the longest period they have continuously run.

          Thanks again for the article/advice Aidan disabling seems to have done the trick.

  6. it seems that that the works. We run that with VMQ and have no issues.

    • The advice from MSFT is to disable VMQ on NICs less than 10 Gbps. In fact, I believe some of them were surprised that VMQ is enabled on some 1 GbE NICs by default.

  7. I am running and still have the problem when running VMQ. Am trying to run VDI under XenDesktop and half or more of the the VMs keep dropping off the deliver group (“Unregistered”) after successfully registering initially. I will try disabling VMQ on all pNICs like you said. is still the latest available driveer from Broadcom, correct?

    • The guidance from MSFT is to disable VMQ on 1GbE NICs. In their opinion, it shouldn’t be on in the first place.

      • I see. Do you have a reference for that? I was looking at best practices here http://blogs.technet.com/b/askpfeplat/archive/2013/03/10/windows-server-2012-hyper-v-best-practices-in-easy-checklist-form.aspx

        and it simply says “VMQ should be enabled on VMQ-capable physical network adapters bound to an external virtual switch.”

        What I am seeing now that VMQ is disabled is that CPU usage is thru the roof, and my VDI density is 50% of what it was with 1GB Intel NICs with VMQ enabled.

      • I’d also like to see that reference material.

        • I can only tell you what the PMs in the networking team for Windows Server advise us … and expect us to share.

  8. Updated 2 hosts (Drivers – Firmware etc) a few weeks ago and have been seeing this random issue since. Thankfully it was only affecting one port on the NIC that was on the vNIC, and it wasn’t a critical port. Access could be restored by flipping the Port on the switch.

    Upon using Get-NetAdapterVmq – I could see that the problematic port was the only one with VMQ enabled. I’ve now disabled VMQ for that and will report back the results…….

    • Just to follow up on this a week later – I’ve not had one drop in connection since VMQ was disabled.

  9. Hi ,
    I have nic 1 & 2 are in teaming in hyper v core os . team name is i have to write in command or just disable the 2 nic one by one?

    • Sorry, I have no idea what you’re asking.

  10. does disabling VMQ – require reboot ? or disconnect of NICS ?

    • NICs will probably temporarily disconnect and reconnect.

  11. Hi,

    We was experiencing the same behaivor.

    The problem has been solved with upgrading iDRAC7 from 1.56.55 version to 1.66.65.

    Note from Dell website:
    2.Intermittent connection issues with iDRAC shared LOM network port.


    Hope it will help you guys.

  12. I m experience same behavior in one windows 2003 R2 VM on Hyper v 2012 R2 Failover Cluster . VM nic loose connectivity , VMQ is diasble on Physical Nic please advice ..

  13. Hi

    Please suggest , we have deployed Windows server 2012 R2 termail services on hyper v 2012 R2 Failover Cluster , we have facing slow login issue on user side , stuck on applied group policy , some hangs ….VMQ is diable on Physical NIC ..
    Your quick response is highly appreciated

    • Sounds like you have an RDS issue that is nothing to do with Hyper-V. Call in tech support.

  14. Hey Aidan,

    Yea I’m having this on the HP Proliant DL360p GEN 8 server. It’s the exact driver file name as highlighted on the article above. It’s killing me, I thought it was something I had screwed up on the config but it has to be this issue!!… I hope!

    Are there any other drivers available yet that I can install does anyone know?

    I will disable VMQ in the morning when I get in…. fingers crossed this will sort it

    Thanks for the article …. hopefully this will save my life ; )


  15. Hi Aidan,

    Same situation here, disabled VMQ on the physical NIC however curious as to what affect that has on throughput. There should be still some offload with RSS remaining enabled?

    With 1GB NICs what is the effective throughput we should be seeing between VM on separate hosts?


    • 1 Gbps

  16. Thanks for the tip. We’re got three Dell PowerEdge R520′s with Broadcom NetXtreme 5720 dual port adapters running Windows Server 2012 R2 and Hyper-V. We’ve been experiencing intermittant network connectivity issues and occassionally the host and one or more guests would lose connectivity to the network, even though everything seemed to be okay.

    After reading your article and Microsoft’s KB2986895 article, I decided to give your fix a go, using the following PowerShell commands:

    Set-NetAdapterVmq -Name “NIC1″ -Enabled $False
    Set-NetAdapterVmq -Name “NIC2″ -Enabled $False
    Set-NetAdapterVmq -Name “NIC Team″ -Enabled $False

    I haven’t had a problem since – touch wood – and it’s been almost a week.

    Our NICs are all running the latest firmware and drivers as of now (25/05/2015)… unfortunately, Dell/Broadcom haven’t fixed the issue yet, but since I don’t notice any downside to switching VMQ off and our servers are now running without networking issues, I’m no longer bothered.

    • Good. There is no downside to disabling VMQ on 1 Gbps NICs – Microsoft has told the OEMs to do this and they were ignored.

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