Do devices still use internet if they are powered off and you have not manually disconnected the WiFi on the device?
OK, iPods, iPhones & iPads can be powered off OR put into Airplane Mode, which stops everything. HOWEVER, WiFi & Bluetooth can still be active when the devices are still powered on and tucked away in your pocket or backpack. The SETTINGS must be used to disable the radios if you don't want to waste battery or gain some privacy.1.devices like IPods, computers, and tablets.
2. So your answer is no if they are and turned off? And I don’t what you mean when you say “but just HOW did you achieve that?”