NC apps : help me!

I want to use my NextCloud (11.0.1 implemented on shared server OVH pro2014) on several devices with many problems
1- On local host ;
Thunderbird lightning work fine
NextCloud local installation, adding : https://my_domain_name/remote.php/dav/calendars/jmy_user_name/personal as new calendar : The remote server did not give us access to the calendar (HTTP 401 error)" (All other address give the same error and curl -u my_username -X PROPFIND https://my_domaine_name//remote.php/dav/calendars/my_username seams to work fine
2- On android 4.2 with DavDroid : DavDroid find my calendar and my contacts, but only calendar work (with google agenda) : list of contacts remain empty. Nextcloud client don’t work (all these applications worked witn OC 9.x)
3- On android 6.0 (and MIUI) : DavDroid Find my calendar and my contacts, but I did not manage to use calendar (I tried with native calendar, Google agenda and aCalendar) : no Caldav calendar proposed. No Cardav contact found in contacts, nothing found in NextCloud client.
For DavDroid, I have to give the IOS address (with “principals”) other addresss don’t work

Certainly there is something I do not do well. I really need help. (And excuse me for my bad English)

I found the solution : it was well hidden !
On MIUI devices, to get it working, you have to add DAVdroid to Device Settings / Security / Permissions / Autostart.
For more certainty, I have also adjusted the applications calendar, contacts and NC client, and, marvelous, its works fine !