[Satcomer]

Always bookmark apple's document "Well Known" TCP and UDP ports used by Apple software products when worrying about ports that Apple uses.

Plus yes for Apple Sharing and iTunes store do need to be in the same subnet (IP local range) to work. The Sharing is for the obvious logical limitation to protect one's data from the big bad world and the iTunes sharing is because of the RIAA & MPAA.

Now open ports on a router is different for each router brand. So always include the router specs & firmware when asking how to open ports on that brand. The routers manual (included in each router retail box) is one's best bet to how to open ports on the router's firewall.