Hyper-V Internet access on one VM but not the other

Delaney Horton 21

I have two VMs residing on my Hyper-V host. One is a Windows 10 and the other is a Windows Server 2016 instance.
I have one external switch created and it is attached to both of the virtual machines.
The Windows 10 VM is able to access the Internet, but the Windows Server 2016 VM cannot.
I have tried removing the switch from the VM and adding it back, but it doesn't make a difference.
How could this be the case when they are both using the same external virtual switch?

11 answers

Dave Patrick 426.1K Reputation points MVP

2022-01-25T21:37:49.47+00:00

I think the external vSwitch is tied to the wrong network interface. If the host has internet access then it's got to be via QLogic BCM5709C Gigabit Ethernet (NDIS VBD Client) #35 (Ethernet adapter Ethernet 5 10.195.44.1 network) since that's the only interface with a default gateway address.

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Dave Patrick 426.1K Reputation points MVP

2022-01-26T13:20:02.477+00:00

Just checking if there's any progress or updates?

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Delaney Horton 21 Reputation points

2022-01-26T18:15:42.047+00:00

I believe that I have the external vSwitch connected to the Ethernet 5 adapter?
The Hyper-V Switch manager doesn't show #35, #36, etc for the adapters so it's difficult to tell for sure, but I have included relevant screenshots so you can see for yourself.
As I mentioned, this is a redeployment on the same physical hosts after running an OS upgrade and rebuilding from scratch. We have set up the external switch in the exact same way, on the exact same physical adapter, but it doesn't work this time.
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Dave Patrick 426.1K Reputation points MVP

2022-01-26T18:48:34.37+00:00

Ok, well then it looks like the addressing may be incorrect for that guest. From what I can tell the default gateway is 10.195.44.1

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Delaney Horton 21 Reputation points

2022-01-26T20:05:33.99+00:00

I do see that this is an issue.
How do you suggest that I go about fixing this?
As I said, we do have a DHCP server on the host network. How can I configure the VMs to automatically be assigned IP addresses from this somehow?
I also still don't understand why IP information isn't being assigned correctly now when it used to work just fine before. I wish I had IP info from before to compare it to.
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Dave Patrick 426.1K Reputation points MVP

2022-01-26T20:08:33.013+00:00

How do you suggest that I go about fixing this?

Delete / recreate the external vSwitch, just make sure it's on the correct network ( presumably 10.195.44.1)

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Dave Patrick 426.1K Reputation points MVP

2022-01-27T13:20:30.14+00:00

Just checking if there's any progress or updates?

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Delaney Horton 21 Reputation points

2022-01-27T18:18:33.193+00:00

As you've seen, in the Change Adapter Settings on the Hyper-V Host, my adapters are named QLogic BCM5709C Gigabit Ethernet (NDIS VBD Client) #35, #36, etc. but in the Hyper-V Switch Manager they are named QLogic BCM5709C Gigabit Ethernet (NDIS VBD Client), #2, #3, etc.
Since it's hard to tell if I'm actually picking the right one through the Switch Manager, I created one using PowerShell since I know Ethernet 5 is what we want the switch connected to:

PS C:\Windows\system32> New-VMSwitch -Name "VDI_External_Switch" -NetAdapterName "Ethernet 5" -AllowManagementOS 1 -Notes "VDI External vSwitch created by Powershell" -EnableIOV:$true Name SwitchType NetAdapterInterfaceDescription ---- ---------- ------------------------------ VDI_External_Switch External QLogic BCM5709C Gigabit Ethernet (NDIS VBD Client) #3

You can see that Ethernet 5 is actually tied to #3 in Hyper-V Switch Manager, and not the first unnumbered one like I had configured before.
Running ipconfig /all on the host shows that the vSwitch now has the correct network address:
169057-ipconfigallvdihost01.txt

However, the Windows 10 VM does not have connectivity to the Internet when attached to the new vSwitch. Here is the ipconfig /all on the VM showing APIPA configuration still:
169183-ipconfigallwin10vm.txt
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Dave Patrick 426.1K Reputation points MVP

2022-01-27T19:09:13.827+00:00

This shouldn't be that difficult. The simplest solution may be to remove both vSwitches, then add back a single vSwitch, trying each adapter until you get it.

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Dave Patrick 426.1K Reputation points MVP

2022-01-31T13:59:13.197+00:00

Just checking if there's any progress or updates?

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Delaney Horton 21 Reputation points

2022-01-31T20:05:11.643+00:00

@Dave Patrick I figured out why the VMs were not receiving the proper IP information when the virtual switch was attached the proper network adapter.
I went to the location that the hosts were physically being kept, and discovered that the host being used for AD/DHCP/Storage services was down due to a failed disk. After replacing the disk, reconfiguring RAID and restoring from a recovery point, the OS is back up and functional.
After rebooting the Hyper-V host, the virtual machines were able to receive the properly IP config to access the internet via the external virtual switch.

This was not a Hyper-V issue it turns out, but an issue of not being able to contact the DHCP server due to disk failure.
Thank you for your time and patience while troubleshooting this.
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Dave Patrick 426.1K Reputation points MVP

2022-01-31T20:06:33.997+00:00

Glad to hear, you're welcome.

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Dave Patrick 426.1K Reputation points MVP

2022-02-01T12:30:15.633+00:00

Just checking if there's any progress or updates?

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