You must be connected to a Wi-Fi network the first time you turn on your HoloLens and set it up. After you have completed initial setup, HoloLens can be used without an active WiFi / internet connection, but with the limitations below.
HoloLens uses WiFi to help identify the space you are in. If you are using HoloLens in an already-used space, you can manually load the space in Settings. Go to Settings > System > Spaces, select the space you want, and then select Load space.
If you are using HoloLens in a new space and are not connected to a WiFi network, you can use HoloLens in Limited Mode. Limited Mode prevents holograms from being placed in your world. In Limited Mode, holograms are fixed to your gaze.
Cortana requires an internet connection for use, so will be unable to respond to most inquiries.
The mic button above the standard on-screen keyboard will be disabled when your HoloLens is not connected to a WiFi network.
Some apps may require an active WiFi and internet connection for use. Each app has different capabilities to be used offline.
HoloLens system updates and app updates will not be downloaded when the system is not connected to the internet over WiFi.