One lan card not detected what to do

when i reached office today, wd dx4000 was showing error that ethernet2 is disconnected. changed the cable, changed the switch port, but nothing, in network cennections it shows two lan connections, but in device manager only one physical lan card.

kindly guide me what to do.

Do you have 2 cables connected?  Some folks have reported this in the past and it just went away?  You have the latest WD firmware updates? Reboot the box?

Yes both lans were connected but suddenly Second one stoped working.

but when I restarted the NAS the second lan started working (after I posted the topic).

now they are working fine.

weird.