iMac loses Network connection overnight

[PapawHam]

I have an iMac on my company network that every morning the user has to reboot to re-establish the network connection.

The iMac shows there is no Network connection.
The system is connected thru ethernet cable from a netgear 4 port hub which also connects a windows 7 PC.

I have had the user work with Apple Tech support, and we just had the iMac in and the Apple Store Tech replaced the Logic Board.

Still have the problem... Any Help would be greatly appreciated.

 

[Gogol]

In System Preferences>Network try to deactivate, apply, activate, apply the ethernet connection. I have this problem too.

 

[macPDX]

maybe not the mac

in our office - it's the server that drops the connection, then
the user has to reset each am. Perhaps not the same
situation with you, but I've heard this particular excuse so
often I've actually begun to believe it.