In a static network there is no need for a nightly Heal Network.
You can do it now and then by hand (menu: Node management).
If Automatic Backup is Enabled they are running at the same moment at 04:00.
I think that's a less happy combination. (04:03 would be a more robust choice)
If you have isolated windows (HR glass in dutch) there is a tiny metal frame inside.from nodes out in the garden and outbuildings
That frame is open for short-wave emissions (sun light) and reflecting long wave emissions (the low temperature in your house)
For Z-Wave, with waves of 34 cm your window is just a metal sheet and very difficult to pass (90% attenuation).
You brick wall is even easier.
Read more here: https://www.domotiga.nl/attachments/dow ... -small.pdf
Via the metal sheet you get wave interference: the direct path to your stick and a reflection via the window.
If you have bad luck, those waves are extinguish each other. With good luck they amplify each other:
Play around in an area of 17 cm (half the wave) to find an optimal transmit/receiver point.