Epicuri assigns each menu item to a particular printer, e.g. a drink prints in the bar and a food item to the kitchen. The printer itself is connected to a router, which automatically assigns an IP address to that printer. The problem is, if a printer looses connection for any reason, e.g. it was temporarily switched off, say, then there's a chance that it won't be assigned the same address again.
Think of the network as a long street of houses, and you have to deliver a takeaway Mr Smith; the label says "Number 17" so delivering to Mr Smith is easy... however if now Mr Smith likes to go to 19 or 21 or 31,303 sometimes, the delivery boy is going to take a very long time to deliver that takeaway! The way we fix this problem is to assign a static address for a device, i.e. Mr Smith will always be at number 17 no matter what.
The only time this model breaks is when you try to attach the printer to a different router, i.e. a different network. Now that static address is no longer valid and it has to be re-assigned.