The main source of slavery in this part of the world in the Middle Ages was indebtedness. In China, impoverished peasants frequently sold members of their own families into slavery, and throughout the entire medieval period criminals or members of their families became slaves of the state.
Nonetheless, NAT can introduce complications in communication between hosts.     * NAT(Network Address Translation) is most commonly used by broadband routers. NAT allows the router to assign non-publically routable IP addresses to the computers on the network.
NAT is a somewhat less commonly implemented than most people think, since what lots of cheap home router manufacturers like to call NAT is really PAT. When you have NAT enabled, whenever a machine from your network requests an outside address, say, 10.10.10.10, your router notes the IP address of the local machine along with the IP address that you're trying to obtain in a NAT table.