I cannot succeed in logging in to my own nextcloud carddav using DAVx5 3.3.5-gplay on a Samsung S7 (Android 8), whereas I can get access to it using other software (cadaver on GNU/Linux, on Android). I tried by the way of the nextcloud android app (which makes uses of DAVx5), same issue. Note that I tried both the login with URL+user name and the advanced login methods.
I get a Configuration detection error: couldn’t find CalDAV or CardDAV service.
It’s a nextcloud 16.0.1 + the official plug-in’s contacts 3.2.0 + calendar 1.7.3 in there.
Should I show the debug-info.txt and logs.txt here? They don’t mean a lot of things to me :-/, I see a “405 Method Not Allowed” during a PROPFIND attempt, then a “Couldn’t detect services on …” followed by a java exception.