Virtual NICs attached to a VM, looses network access

Hi Experts,

I have a Hyper-V 2012 R2 server with two VMs on it, both are running a virtualised 2008 R2 server. On the VM in question, it has lost network access three times and I get it back on the network by changing the vNIC to another one. Then a week later (always at night), that NIC looses connection so I put it on the same NIC that the server VM is on as that has no issues with network access.

I have removed the V NIC and added it again, but it did not make a difference.

I have Hyper-V Replica set up on both VMs (5mins)  and Altaro backing up both VMs to an iSCSI NAS.

The NIC is a default setting with no VMQ and no SR I/O enabled.

Does anyone have any ideas?


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ste5anSenior DeveloperCommented:
hmm, never had such a problem. Have you looked at the physical network? No errors?
Robin CMSenior Security and Infrastructure EngineerCommented:
Without being able to dig around on the system this is potentially going to be tricky to diagnose. I have lots of questions:

I'm not sure what you mean by "changing the vNIC to another one"  - another what?
What is the uplink to the host?
Is it using shared or dedicated uplinks to the virtual switch?
Are you using a trunk/VLANs into the virtual switch?
Do you have any other VMs on the host on the same VLAN that either do or do not exhibit the same problem? If you don't, can you add one and see if it does/does not also have the problem?
Is there anything in any of the Event Logs (either on the host or within the VM) that indicate any networking problems?
How does the problem exhibit itself within the VM? Does Windows think the NIC is unplugged?
Are you using DHCP in the VM and does the VM retain a valid IP address after the problem occurs?
ggnttAuthor Commented:
sorry for leaving this question.

We downgraded the driver with HP help, as the new one was just out.

Never had the issue since.


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ggnttAuthor Commented:
We downgraded the driver with HP help, as the new one was just out.

 Never had the issue since.
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