Server 2016 Hyper-V Virtual Switch issues

Susan Dodds 186 Reputation points
2021-10-14T14:58:39.267+00:00

I have 2 server 2016 Hyper-V servers.

Both servers have experienced issues where the Virtual Switches become corrupted after rebooting the Hyper-V host for windows updates.

By corruption, I mean the virtual machines still have some network connectivity but not all. They can see the internet but applications do not work properly, like Exchange, DC replication, SharePoint.

The only way to fix this is to move the VM's to a different virtual switch port, delete the original virtual switch port, re-create that same port, and then move the VM's back to that port.

This has happened on 2 Hyper-V servers with different hardware.

The most recent incidence also caused issues with a backup software program running on one of the Hyper-V hosts until it was rebooted, the host experienced the same symptoms as the VM's, even after the virtual switch was re-created until the reboot.

Is there any way to prevent this?

Thanks.

Hyper-V
Hyper-V
A Windows technology providing a hypervisor-based virtualization solution enabling customers to consolidate workloads onto a single server.
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  1. Dave Patrick 426K Reputation points MVP
    2021-10-14T15:04:34.34+00:00

    virtual machines still have some network connectivity but not all.

    How are you evaluating this?

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  2. Susan Dodds 186 Reputation points
    2021-10-14T15:06:35.553+00:00

    They still have internet access, can talk to the hosts, but not other computers over the network. Net based programs like Exchange and SharePoint don't work beyond the host.

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  3. Dave Patrick 426K Reputation points MVP
    2021-10-14T15:09:28.633+00:00

    This sounds like some sort of firewall issue. I'd check to see that all still have the domain network profile and no multi-homed domain controllers. Also check that the domain controller and problem members all have the static ip address of DC listed for DNS and no others such as router or public DNS.

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

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  4. Susan Dodds 186 Reputation points
    2021-10-15T03:35:50.44+00:00

    No changes made in any firewall or DNS.

    When changing virtual switch port assignments, the virtual machine doesn't care as long as it has one so the virtual machine network profile doesn't change when changing/deleting/re-creating virtual switch ports on the host.

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  5. Dave Patrick 426K Reputation points MVP
    2021-10-15T13:30:35.13+00:00

    No changes made in any firewall or DNS.

    Not suggesting this. You'll need to check the next occurrence. I'd also check to see that all still have the domain network profile and no multi-homed domain controllers. Also check that the domain controller and problem members all have the static ip address of DC listed for DNS and no others such as router or public DNS.

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