I had a very strange problem after running Windows updates this morning on all 3 of our Domain Controllers running Windows 2012 Standard on ESXi 5.5 (build ID 2403361). After reading numerous articles telling me VMXNET3 adapters are the way to go I tried what was quite possibly the dumbest fix ever.
We already had VMXNET3 because this has happened before on e1000 adapters so we made the change a while back.To fix the problem I did the following:
1. Open the vSphere Client and find the VM
2. Right-click and "Edit Settings"
3. Remove the network adapter then add the same adapter back using the add hardware wizard choosing VMXNET3
4. Click "OK" to apply the change
5. After a quit blip in your Remote Desktop Session you should see your internet connection back to normal.
And the Internet Returns!