Why am I not supposed to use the freenet package supplied by Debian?
The freenet package that can be found in Debian’s software archive is several years old. As Freenet is still a lon way from a 1.0 version, there is still a lot of development going on, even on the communication protocol between the nodes. To aid in this development, a node will refuse incoming connections from nodes which are too old. A node installed from the Debian software archive would simply not be able to connect to the current network.