Thanks to a very nice person we met at Nextcloud conf 2017 we were able to personally take some important screenshots from a Xiaomi device and managed to find out what you need to do to get DAVdroid working with Xiaomi devices. Please have a look at these screenshots and on the colorized sections (stuff that belongs together is colored (orange, blue and pink) the same way).
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Don’t forget to also remove your battery restrictions (if you want DAVdroid to sync automatically):
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