Use cellular when connected to wifi Is there a possibility to force an android phone to use cellular data when connected to wifi. For iOS I've found this https://apple.stackexchange.com/questions/173894/can-i-connect-to-wifi-but-still-use-cellular

Regards,
Nils
I'm pretty sure you cannot do that as the phone needs to connect to one protocol at a time.  I have a Wi-Fi hard-drive and the manufacturer of the device states that once you connect to the device you will need to either turn the device off to get cellular signal again or disconnect from it.