U mode

U means UDP binding mode. The LWM2M Server expects that the LWM2M Client is reachable via the UDP binding at any time. The LWM2M Server must send requests to a LWM2M Client using the UDP binding. The LWM2M Client MUST send the response to such a request over the UDP binding.

The U binding mode is unlikely to be suitable for devices that only connect intermittently such as Cat-NB1, CatM1 or LORAWAN as most of the time the device is offline.

This is the default mode of operation.