I second this request, having the same use case as BigRed. Maybe a server side solution would be useful, but DAVdroid should offer a reminder filter, too.
Nextcloud has an open issue for this: https://github.com/nextcloud/server/issues/679
Enhancement request: Currently you have to enter the wifi network names you want to automatically use to sync with, manually. It would be nice to provide a checkbox dialog with all available networks to minimize the possibility of typos.