I have a Synology DS223J and I am using Cloud Sync to sync via WebDav to IceDrive.
For the second time in two weeks, all of a sudden our entire folder structure got moved into recycle bin and re-downloaded from Icedrive - but with the todays date on all the files.
I have found out that this coincided with our ISP / IP Phone provider adjusting some settings and restarting the router - which gave us a different WANIP.
As I do not know much about how Cloud Sync or WebDav or Icedrive operate on a network level, why do you think this [change of WANIP] would cause a re-download all our files?