The maximum distance that the Bublcam can remain connected to and operate from a device is about 10-20 meters depending on various factors such as the device specifications and your environment (overcrowded channels, WiFi interference, walls, doors, etc.).
You may notice that your preview won't load after a certain distance. However, often times you will still be connected to the Bublcam (if you have not yet received an error message stating that you are disconnected) and can still capture bubls from this distance. You can see if you're still connected to the Bublcam by checking your WiFi network settings for "Bublcam_xyz".