If you want minidla to accept connections from the rest of the world, please
add
networking.firewall.allowedTCPPorts = [ 8200 ];
networking.firewall.allowedUDPPorts = [ 1900 ];
to /etc/nixos/configuration.nix.
See <http://lists.science.uu.nl/pipermail/nix-dev/2013-November/011997.html>
for the discussion that lead to this.