Hi,
Zephyr 2.1.0 will be released 2019-11-29, and it will support LwM2M Queue Mode which is an important feature for sleepy devices, see https://github.com/zephyrproject-rtos/zephyr/issues/6162.
Do you have a roadmap/plan for when Zephyr 2.1.0 will be integrated in nRF Connect SDK?
BR / Bjorn