We have a Dell PowerEdge R320 server running Windows 2012 (not R2) that will randomly lose network connectivity. This happens every few days and when it happens, (from the console) I can see that the network adapter is still active, shows the cable is plugged in, but TX and RX bytes don't increase. I can regain connectivity by either unplugging the network cable and plugging it back in, disabling and enabling the adapter, or rebooting. Event viewer shows no errors, warnings, or other problems during or before this time.
I've tried replacing the network cable and moving the server to a different port on the switch, putting the latest firmware and drivers on the server (including network drivers), running checkdisk and SFC scan and applied the latest Windows updates. Has anyone else seen this issue? Anything else I should try?