The Router is a machine able to move items into or out of machines or inventories it is attached to and is able to take 6 upgrades. The Router must be connected to a network of machines (machines are defined as having an inventory slot) for it to work. The network of machines can be as large as desired but all the machines in the network must be connected. Do note that Routers will not function when a redstone signal is applied.
The Item Router has a number of upgrades that can be applied to it by shift-right-clicking the router with the item in hand. This will add a “–” button in the GUI, which you can press to look at each upgrade. To remove an upgrade, press Delete while hovering the mouse over the button. (on your keyboard)
The speed boost upgrade increases the rate at which the router processes items. The way it does this is by taking away the "search" time of the router. This upgrade is only really useful in very large networks of machines.
The Bandwidth upgrade allows the Router to process a stack of items at a time instead of individual items.
The machine filter upgrade allows the item router to include or exclude certain types of machine it's connected to, as well as picking nearby (adjacent) routers or every type of a certain machine. For instance, you may only wish the machine to visit barrels, and after one barrel is connected you should easily be able to set the filter.
The Item Filter upgrade allow the Router to be set to include or exclude specific items. For instance, setting it to Cobblestone will allow the machine to insert/extract only cobblestone from the system.
When the router is on Extract mode this upgrade allows the Router to eject its contents in any direction. It can be ejected up, down, North, East, South, or West. If you are ejecting into a machine then whatever side the machine is attach to the router is where the ejected item will go. Note: It can eject(extract) and insert at the same time.
- For instance, to add Iron Ore to a furnace (the router is extracting out of a chest and ejecting in a direction) the furnace must be below the router because the top slot of a furnace is the input slot and so the ejector upgrade must be set to eject to bottom.
This upgrade will completely fill a machine before moving on to the next. (note, this upgrade is currently bugged)
This video demonstrates everything you need to know about storing items with The Router.