After completing the setup, disable the Pi’s other network interfaces to ensure that all network communication goes over cellular:
I would also like to to run a wlan connection to a hotspot at the same time. Could someone suggest any pointers to achieving this? Or does this statement suggest that when you have proper comms to the USB modem then you could try other connections?
Found this thread:
Cloud send message not received over ppp? which seems to suggest that I could do this by using policy based routing. Correct?