Although your internet connection is 1Gbps various factors will mean that you will not necessarily get this speed on your computer or device.
You can connect your devices in two ways: Ethernet or WiFi.
To get the maximum speed available you will need to use a wired (Ethernet) cable connecting your computer directly to the router. You must also have a Network Interface Card (NIC) in your computer that can communicate at 1Gbps or above. Many older computers will have an NIC that can only communicate at 100Mbps so that is the maximum speed you can expect using an Ethernet cable. cozlink.com has a very handy guide to help you find out what speed your computer is capable of.
The router supplied by MyFi is capable of a maximum speed of 300Mbps via WiFi. However, the speed you will achieve will depend on where you are located in relation to the router, the structure of the building and your device. Walls and distance will affect the speed you obtain, the further you are away from the router the slower speed you can expect. You can boost the speed of your WiFi around your property by using WiFi repeaters. The latest Mesh WiFi systems can improve the speed throughout your property.