Cannot connect to calendar, caldav

hi everyone

I run owncloud-9.1.5-1.el7.noarch off Centos 7

I have a calendar working, so it seems, but when I try to connect to it from Thunderbird and likes I fail.
Thunderbird just keeps asking to authenticate, which I do using same credential I login to Owncloud.
As caldav url I use the one Owncloud gives out when click "Link", but I also tried iCal from settings.

Strangely on apache's end, in log: - - [24/Nov/2017:16:47:05 +0000] "PROPFIND /owncloud/remote.php/dav/ HTTP/1.1" 401 414 - - [24/Nov/2017:16:47:05 +0000] "PROPFIND /owncloud/remote.php/dav/ HTTP/1.1" 401 414 - - [24/Nov/2017:16:47:13 +0000] "PROPFIND /owncloud/remote.php/dav/ HTTP/1.1" 401 414

Is it Thunderbird problem, I am missing something trivial?

Now that I've fixed OC logging, in logs when I try to connect in a web browser to URL of the caldav I see:

{"reqId":"Whh1EMzVRPxavlJ6IPQ9cgAAAAk","remoteAddr":"","app":"webdav","message":"Exception: {\"Message\":\"HTTP\\/1.1 401 No 'Authorization: Basic' header found. Either the client didn't send one, or the server is mis-configured, No 'Authorization: Basic' header found. Either the client didn't send one, or the server is mis-configured\",\"Exception\":\"Sabre\\DAV\\Exception\\NotAuthenticated\",\"Code\":0,\"Trace\":\"#0 [internal function]: Sabre\\DAV\\Auth\\Plugin->beforeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#1 \\/usr\\/share\\/php\\/Sabre\\/Event\\/EventEmitterTrait.php(105): call_user_func_array(Array, Array)\n#2 \\/usr\\/share\\/php\\/Sabre\\/DAV\\/Server.php(446): Sabre\\Event\\EventEmitter->emit('beforeMethod', Array)\n#3 \\/usr\\/share\\/php\\/Sabre\\/DAV\\/Server.php(248): Sabre\\DAV\\Server->invokeMethod(Object(Sabre\\HTTP\\Request), Object(Sabre\\HTTP\\Response))\n#4 \\/usr\\/share\\/owncloud.clustered\\/apps\\/dav\\/lib\\/Server.php(178): Sabre\\DAV\\Server->exec()\n#5 \\/usr\\/share\\/owncloud.clustered\\/apps\\/dav\\/appinfo\\/v2\\/remote.php(30): OCA\\DAV\\Server->exec()\n#6 \\/usr\\/share\\/owncloud.clustered\\/remote.php(164): require_once('\\/usr\\/share\\/ownc...')\n#7 {main}\",\"File\":\"\\/usr\\/share\\/php\\/Sabre\\/DAV\\/Auth\\/Plugin.php\",\"Line\":188,\"User\":false}","level":0,"time":"2017-11-24T19:37:52+00:00","method":"GET","url":"\/owncloud\/remote.php\/dav\/calendars\/pe\/personal\/","user":"--"}

And I think that above logged info is identical when I try with Thunderbird.

I did the following search and found which seems to be about Thunderbird as well and which is pointing to various resources you could check.

I've also searched a bit, but before I go on a search again...

When I use web browser, any, and I go to url(s) owncloud gives I cannot get pass authentication neither.
Does it not say it's not client problem?

Calendar's url eg.
Does the above url not look strange? This is what "Link" gives, then from "Settings & Import":
and as caldav for iOSes

none of those urls I could, with web browsers get to authenticate successfully.

I'm using URLs like http://mycloud/remote.php/dav/calendars/myusername/mycalendar/ which are working fine.

Where from in your owncloud do you get that URL?

I get this link if i'm clicking at the three "dots" at the left of one my calendars and choose "Link" there.