Looking for a VPN or tunnel of some sort suitable for use in IOT applications. Ideally i could have a sim card with a ~10mb data cap costing allmost nothing and a VPN for debugging, snmp and such. But most VPNs i have tested (IPSec in particular) use quite a bit of data as part of their keep alive scheme.
Applications of my iot routers are amongst others, EV chargers, door locks, building automation ++
Just to be clear, i am fully aware that there are control traffic over a VPN, and that it is necessary. I simply want some of you guys experiences with this.