With latest update the all lights offline problem got back to me. With version before I didn't have this trouble anymore. Now it seems back.
Rebooting router didn't help. After rebooting my mobile all my rooms are missing and still no bulbs get detected! :-/
When not being connected with my WLAN (connected through mobile network) it instantly works again and rooms are back too. Seems to be the problem with guest WLAN again?! Using Xiaomi R2D router.
After connecting with WLAN again I can control the bulbs I controlled while being on mobile network all others are not responding on commands.