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MikaelHallen-0088 avatar image
1 Vote"
MikaelHallen-0088 asked PaulEPCS-9423 answered

No network access for one VM (6 running fine). Hyper-V

I have a Hyper-v environment that have been fully functional for years.

As of yesterday my file server no longer can access our network. No network access.
I can reach it through our hyperv servers and have tried restarted it and resetting ever since.
I have 6 more VMs that connects without problem.

The VM is server 2019. Hyper-V servers are 2012.

I have one more 2019 server and the only difference in network setup is the driver of the NIC.
Microsoft Hyper-V Network Adapter - 10.0.17763.2145 (driver date 2006-06-21) not working
Microsoft Hyper-V Network Adapter - 10.0.17763.1577 (driver date 2006-06-21) which is working.

I find it hard to believe that this driver is causing the problem but it is the only difference I have noticed.

Tried both static and dynamic IP for the server, no luck.

I have deleted and added the network adapter several times.

I have deleted one of the virtual switch and added a new one. tried the new switch with other VM and it works.

but my file server still has no network access.

Any thoughts?

windows-server-2019windows-server-hyper-v
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Same problem. We tried removing the KBs without luck. I guess we are waiting for a fix. I'm currently using the legacy adapter while this is resolved.

1 Vote 1 ·

I've run into the exact problem. Installed from the Aug_2021 ISO, which comes with 10.0.17763.1879 of the Microsoft Hyper-V Network Adapter. Networking worked fine at that point. Eventually I decided to run Windows Update, which didn't offer much. But on rebook, the driver had been updated to 10.0.17763.2145, and I lost all network access. Nothing I did could get it working again. Installing all the updates I could didn't help, so I suspect one of the uninstallable updated did the deed.

I ended up reinstalling from scratch, and resisting the temptation to run Windows Update for now.

This is definitely something introduced in a recent update. Showing as available now (and I'm not taking them):
KB5005568 and KB4535680, plus one Defender AV update and an update to the Malicious Software Removal. I suspect the latter two aren't related, it's one of those other updates. I'm suspecting the first one: 2021-09 Cumulative Update for Windows Server 2019 (1809) for x64-based Systems (KB5005568).

0 Votes 0 ·

I'm also seeing the same behavior after installing KB5005568 on Server 2019 VMs running on a Server 2012 Hyper-V host. For me it's been very consistent across three Server 2019 VMs so far- install KB5005568 and network access stops; remove KB5005568 and it comes back. It's a Dell R910 with Broadcom/QLogic NICs, and the symptoms are the same as what's described in https://docs.microsoft.com/en-US/troubleshoot/windows-server/networking/vm-lose-network-connectivity-broadcom, although that article obviously pre-dates the Sept.2021 CU. I updated the physical NIC drivers to the QLogic 17.2 release and disabled virtual machine queuing on all of them anyway, but that hasn't changed the behavior. I hadn't checked the virtual NIC driver versions before reading this post but on a post-KB5005568 VM (non-functional network) it's 10.0.17763.2145, and on one with KB5005568 rolled back it's 10.0.17763.1 (and the network is accessible).

So the Sept. 2021 CU (KB5005568) on the VMs definitely seems to be the problem, or what triggers it anyway.

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Since this is mostly a test VM, I decided to upgrade it to Windows Server 2022. Which upgraded the driver. Which broke networking. So it's much more than just 2019 September CU, but also the latest version of Windows 2022.

One thing I noticed with this driver update is I have a whack of "WAN Miniport" drivers that weren't there before.

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I haven't installed 2022 anywhere yet but I can at least say that pre-2019 versions don't seem to have the same issue. Two Server 2016 VMs and one Server 2012 R2 on the same host still have functional networking after their respective September 2021 CUs.

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We encountered the same issue. Purchased new copy of Server 2019 Standard w/CALs. Setup new VM with previously used Virtual NIC Settings.
All was well until installing Windows Updates. After Windows Updates the server could not connect to any networks.
We tried different Virtual NICs and TCP reset commands. But nothing worked, until removing the windows updates. We removed the following, then we are able to connect to a network:
KB4514366, KB4512577, KB5007206.

Looks like we will also be waiting for Microsoft to correct this issue, before anymore Windows Updates.

0 Votes 0 ·
DSPatrick avatar image
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DSPatrick answered

An unedited ipconfig /all of working / non-working may help.


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MikaelHallen-0088 avatar image
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MikaelHallen-0088 answered

of course. first is working second is not.
128780-image.png


128804-image.png



image.png (57.8 KiB)
image.png (22.6 KiB)
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DSPatrick avatar image
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DSPatrick answered

Is the top a domain controller?


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MikaelHallen-0088 avatar image
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MikaelHallen-0088 answered

both are domain controllers

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DSPatrick avatar image
0 Votes"
DSPatrick answered DSPatrick commented

Please run;

Dcdiag /v /c /d /e /s:%computername% >C:\dcdiag.log
repadmin /showrepl >C:\repl.txt
ipconfig /all > C:\dc1.txt
ipconfig /all > C:\dc2.txt
ipconfig /all > C:\dc3.txt

then put unzipped text files up on OneDrive and share a link.



· 1
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Just checking if there's any progress or updates?

--please don't forget to upvote and Accept as answer if the reply is helpful--



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LimitlessTechnology-2700 avatar image
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LimitlessTechnology-2700 answered

Hello Mikael H,

Have you already tried to update virtual machine configuration version after implementing the new driver?

Best regards,

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BradSmith-8843 avatar image
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BradSmith-8843 answered JayB-4803 commented

Okay, looks like I solved it on my Win 2022 VM, and hopefully we can apply the equivalent solution for 2019.

I checked the Update Catalog at https://www.catalog.update.microsoft.com/ to see what was latest for Win 2022, and there's a Cumulative Update Preview dated Sept 24th. KB5005619.
Downloaded that, used IsoCreator to turn it into an ISO, which I could then mount on the VM, and ran the .msu within. Rebooted, and presto!
The new network driver reports v10.0.20348.1.

The latest update that reports itself for Server 2019 is KB5005625, dated Sept 21st. Maybe that'll work for you. If not, hopefully the next one.

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Has anyone tried this for 2019? I'm having the same issue and have disabled updates on the VM for now.

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Applying that .msu in 2019 failed for me. Also, KB5005625 is already installed. I'm currently using the legacy NIC but I got very little traffic on this machine.

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The Preview update for 2019 (KB5005625) did not work for me on the two VMs where I tried. It seems to have the same driver version as before. I added a legacy adapter to one and that seems to work, and I replaced the netvsc.sys file version 10.0.17763.2145 on another VM with an earlier version and that also restored network access after a restart. So those would be options for temporary fixes if you're in a bind, but hopefully an official supported fix is coming...

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For those keeping score, the October CU (KB5006672) updates the network driver to 10.0.17763.2237 but the problem persists

1 Vote 1 ·
Andy-De-Deckker avatar image
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Andy-De-Deckker answered

Same problem here. Running vms on Server 2019 on a hyper-v running 2016.
Had to uninstall the September CU on the VMs. Running stable on the August CU now.

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MatthewLyons-8647 avatar image
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MatthewLyons-8647 answered
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AussieCraig-3509 avatar image
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AussieCraig-3509 answered

We encountered the same issue with last month's updates - both our WS2019 VMs running on 2012 Hyper-V Cluster lost networking after installing KB5005568. At the time we hadn't installed the Sep patches on our hosts, so I decided to disabled Windows Updates service on the VMs and try again in October, after patching hosts and hoping that MS will have recognised the issue and fixed it with October updates.
Alas, as others have noted above, the October KB5006672 causes the same problem. I'm about to uninstall it and disable Windows Updates again.
Moving the Hyper-V cluster upgrade up the to do list...

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