Series 1 3D printers connect to your computer using a network connection. This connection can be made in one of two ways, 1) by plugging your Series 1 into your router, and 2) by connecting your Series 1 using its on-board WiFi.
Connecting your Series 1 via WiFi is pretty darn cool, but as with any wireless technology, the signal strength will weaken and fail if your 3D printer is too far from your wireless router. Connecting your Series 1 to your router using its included Ethernet cable is a sure fire way of avoiding this type of problem. Best of all, if you're using a wireless router, your computer can still be wireless and connect to the Series 1. Check out these instructions to connect to your router using Ethernet:
Don't worry if your router is inconvenient to access, as the Series 1 and Series 1 Pro ship with on-board WiFi. Just make sure that your Series 1 is located close enough to the router for it to receive a strong signal. Check these instructions out to connect using WiFi only: