Networking randomly dies on a 2012 R2 vSphere VM

Strange issue. Simple solution.

We had a Windows Server 2012 R2 Domain Controller sitting on vSphere 5.5 (2068190) which would randomly lose it’s network connection.

When you logged into the system locally the network interface appeared to be up but you could not connect to anything outside of the VM.

If I rebooted the VM it would work for a few hours or less and then the network would drop out again.

Digging through the event viewer I came across these:

The VM had a E1000 NIC attached to it. I figured the issue was the VM NIC model and got some backup to my theory from here:

The solution appears to have been removing the E1000 NIC and adding either a E1000E NIC or in my case a VMXNET 3 NIC.

One thought on “Networking randomly dies on a 2012 R2 vSphere VM

  1. There is a slight performance penalty when you use the emulated NICs as well, since emulation takes up some host CPU cycles to make sure the NIC performs just like an Intel. This article gives some nice real world stats:

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