The fourth generation AppleTV, with Plex, is connected in LAN via Ethernet connection.
The LAN is managed by TimeCapsule which has 4 ethernet and USB sockets. To the USB jack of TimeCapsule it is positioned a small hub liabilities with 4 USB ports connected to simple HD with USB ports of type 2 and 3 where there are video files (movies, etc.). Other video files are also present in the HD inside an iMac connected to the LAN only via wifi (is the computer where the videos are processed).
Under these conditions the movies into the internal HD of iMac and into the USB HD connected with USB HUB to TimeCapsule seen perfectly.
I have connected an external HD via Thunderbolt iMac and moved some videos from internal HD to external HD to check the possibility of seeing them via AppleTV: but apparently Plex can't see the movie on the external thunderbolt HD, it's strange because Plex can "see" well the internal HD iMac and external HD connected via USB to TimeCapsule.
Someone can suggest a solution?