I can't access my media files over the network

By default the Core only listens for network connections on the internal network. We recommend using dual network cards in the Core so it can act as a firewall and separate the internal network from the outside one. However if you have only 1 network card, or if you want to access the network from the external network, then in LinuxMCEAdmin, choose Advanced, Firewalls, and there you can open ports.