The 'Shared' section disappeared in Finder on my iMac. I checked the Finder-settings, but couldn't find anything to bring it back. I decided to reboot my iMac and now 'Shared' is back. I only had to reconnect my NAS using cmd-K (normally the NAS automatically shows up). So everything is OK now, but I wonder why this 'Shared' suddenly disappeared in Finder. Could it be that I accidentally typed some key-combination? Finder-glitch?