Does the adapter within the guest OS dissapear or the actual vmxnet3 nic in edit settings on the VM itsself?
In my experience I added the following perameter to stop users acciedentaly disconnecting there adapters by right clicking on it in the tray.
you can do this by doing the following:
"edit settings" on your vm or Master image then > "options" Tab then > "General" and> "config peramaters"
add a row and insert this.
name value
devices.hotplug | false
hope that helps