I'm running ESXi 5.5 with three VMs on it. Two of the VMs are not actively used but are up and running. The third VM (Windows Server 2012 R2) is currently being used to store data backups, so a fair amount of data is transferred to it daily. For some reason, over the past few weeks, this VM has been losing network connectivity, it seems, typically sometime at night after the backup. The event logs will show errors relating to loss connectivity, but, unless I missed it, nothing noting why it happend.
Repairing the network connection will resolve the issue, but it will happen again a few days later. While the network is down on this VM, I'm still able to access the other two VMs without issue. Any idea what could be causing this?