i have the feeling it has something to do with this problem here:
How is your server (apache2) configured?
for the fpm I added those lines
<FilesMatch "\.php$">
SetHandler "proxy:unix:/var/run/php/php7.0-fpm.sock|fcgi://localhost/"
</FilesMatch>
<Proxy "fcgi://localhost/">
</Proxy>
I also get this log message (but without your further lines):
**{âreqIdâ:âYN3JCoOUYTXYid3IVeRjâ,âlevelâ:0,âtimeâ:â2018-03-23T15:42:27+00:00â,âremoteAddrâ:â192.168.2.8â,âuserâ:âââ,âappâ:âwebdavâ,âmethodâ:âPROPFINDâ,âurlâ:â/remote.php/webdav/â,âmessageâ:âException: {"Exception":"Sabre\\DAV\\Exception\\NotAuthenticated","Message":"No âAuthorization: Basicâ header found. Either the client didnât send one, or the server is misconfigured, No âAuthorization: Bearerâ header found. Either the client didnât send one, or the server is mis-configured","Code":0,"Trace":"#0 [internal function]: Sabre\\DAV\\Auth\\Plugin->beforeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#1 \/var\/www\/nextcloud\/3rdparty\/sabre\/event\/lib\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#2 \/var\/www\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(466): Sabre\\Event\\EventEmitter->emit(âbeforeMethodâ, Array)\n#3 \/var\/www\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Server.php(254): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#4 \/var\/www\/nextcloud\/apps\/dav\/appinfo\/v1\/webdav.php(80): Sabre\\DAV\\Server->exec()\n#5 \/var\/www\/nextcloud\/remote.php(164): require_once(â\/var\/www\/nextclâŠâ)\n#6 {main}","File":"\/var\/www\/nextcloud\/3rdparty\/sabre\/dav\/lib\/DAV\/Auth\/Plugin.php","Line":168}â,âuserAgentâ:âMozilla/5.0 (Linux) mirall/2.3.3 (Nextcloud)â,âversionâ:â13.0.1.1â}
**