Google had been internally testing a feature named “Instant Tethering” for a while now. Essentially, this feature allows devices to share their cellular data connection through Wi-Fi, automatically and seamlessly. Automation is the crucial part of this feature, as previously we would have had to manually create hotspots on our phone and manually connect to them from other devices.
Instant Tethering is now rolling out to support Pixel and Nexus devices through an automatic update to Google Play Services.
To initiate this feature, users first need to toggle it by going to Settings -> Google -> Instant Tethering, if it is not already enabled. Selecting the ‘Provide data connection’ option will mark the device as host, while the ‘Get data connection’ option marks the device as a client.
When a client loses internet connectivity but the host still retains internet access through a cellular data connection, the client will display a prompt asking you whether you want to connect to a hotspot. Choosing the ‘Connect’ option will automatically create a secure hotspot connection between the two devices. This eliminates the need to interact with the host device to initiate a hotspot whenever a client loses connectivity. To preserve battery, the connection will stop after 10 minutes of idle time with no usage.
Currently, host mode is available on the Pixel, Pixel XL, Nexus 6, Nexus 5X and Nexus 6P on Android 7.1.1 and up. Client mode is available on these devices as well as the Pixel C and Nexus 9 on Android 6.0 and up. The host and client must be signed on the same Google account, and must have Bluetooth and WiFi switched on throughout.
Via- xda- developers