Calendar synchronization

I using iCloud’s calendar qui extensively, it’s my todo list sort of. It works fine on the desktop, synchronizing with the clouds. But, for now years, I have problems synchronizing with my iPads. (mini 4 and iPad Pro) and iPhone (4, 6, 8). I always have to shutdown - restart the devices about every day / every 2 days to force synchronizing. With iOS 11, the swipe down to refresh doesn’t seem to have an effect (yes I tried 20 times, many times, but nothing is happening).
I had a (small) relief this summer when I didn’t had to shutdown-restart in July and August ! Calendar synched well… But since Sunday (2nd September), sync “broke” again… Since, I’ve restarted my iPhone 3 times, and iPad 4 times (we are Wednesday 5).
I tried to change the sync settings to Push, Retrieve? (récupération) or manual, with no better success.
I’ve many accounts set up, but only 1 for calendar, the iCloud one. Has anybody a clue why sync stops like that ?
(Calendar is the only service with a sync problem, Notes, Photos are working fine)

Thanks !

when you enter a calendar event on your iOS device does it show up on other iOS devices?

When there is no sync visible, adding a calendar event on the iPhone doesn’t show up on my iPad. (same from iPad).

So for another unkown reason, since this morning after a X-th reboot of iPad and iPhone, sync seems to work again up to now… don’t ask me what happened :wink: