A few servers running Server 2012 Standard edition running on esxi 5.1 continues to lose network connectivity. When I console into the server, I see a red X on the network. I run the "Troubleshoot problems" wizard and receive the message in the screenshot "The default gateway is not available". Using the "Try these repairs as an administrator" resolves the problem as does rebooting, but the problem returns later.
A lot of posts for this problem in Win7 relate to NIC drivers, but this is VM. I uninstalled the VMware tools and that did not solve anything. Adding them back in did not solve it either. I have only seen this problem on a Surface Pro and these servers, so Win8 and Server 2012.