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JackThunder's avatar
JackThunder
Copper Contributor
Mar 08, 2025

Untagged VLAN - Server 2025 Hyper-V

Hi,

I have a strage issue and not finding a solution.

 

Using Server 2025 with two node Hyper-V cluster. Most of the machines using VLANs which works fine.

Some machines using no VLAN config. Which usually means the "Access VLAN 1" regarding our switch configuration.

With Server 2019 this worked fine.

With Server 2025 same NIC port, same server/NIC hardware "Untagged" VMs don't get any network connection. If I add a second NIC to the VM "Untagged" the NIC get immidiatly an IP address and has a proper connection. If I remove the first NIC, the second NIC stop working.

 

It looks like something has changed with Server 2025 (maybe already with Server 2022). Do you have any idea what kinde of problem I have found?

Thanks

Jack

Hyper-V
Networking
Windows Server
  • Largelos's avatar
    Largelos
    Copper Contributor
    Apr 16, 2025

    I have no issue with untagged or access vlan VMNetworkAdapter configuration, but vlan trunk seems doesn't work with external VMSwitch at win2025. After "set-vmnetworkadaptervlan -trunk" configuration, VMSwitch only able to forwarding traffic inside hyper-v host for this VMNetworkAdapter, and provide no external NIC connectivity for this interface.

  • JackThunder's avatar
    JackThunder
    Copper Contributor
    Mar 13, 2025

    Installed 03/25 updates. Sadly the problem still exists. But now I have to add three NICs to get it working. First NIC and second NIC get not connection. Can anyone confirm the issue? Usind Dell OS10 switch as backed.

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