Does anyone have experience using RAI (Release Assistance Indication) with LwM2M?

I can think of three cases when this is useful:

1. Observe notifications (both CON and NON)
2. LwM2M 1.1 Send operation
3. Close connection (de-register and after bootstrap-finish)

In other cases the device does not know if the server wants to send more.

Is it possible to configure an application server which uses IPv6 only?

When trying this I always get an error.