This is the correct link for WebDAV access to your files. The web browser/WebDAV client will then send login credentials along with the request, and the user name from the login credentials determines whose files you’ll see. If no login credentials are sent, the server will reply with a “401” error (“unauthorized”), causing the client to request login credentials from the user.
So it seems your Finder sends login credentials for admin. I have no idea why, though; I don’t use macOS.
Throughout the tests I was always logged in via web access as admin.
I used the same client for connection setup with WebDAV.
During the connection setup for WebDAV, the UCS server obviously did not ask the client for new credentials, but simply use the existing (web) connection.
It seems then that the server no longer requests new access data because of the existing connection.
After logged out of the web, the user credentials at the client were immediately queried and used.
Since the problem obviously goes out from the server, I do not sign the thread as “solved”
No, there is no problem on the server side. Looks like Nextcloud is using SAML/single sign on. In that case not asking for new credentials while you’re logged in to the UMC is working as intended.
Whenever you want to test anything web-based wrt. authentication, I highly recommend using either a second browser that isn’t logged in anywhere or using your browser’s anonymous/private window functionality as that won’t share state ( = cookies, session information) with the regular browser windows.
Still, always use a private mode browser window for testing authentication issues, especially when you’re signed in to something (Nextcloud itself!) in your regular browser window.
Finder store the credentials in different containers in the keychain.
For WebDAV it is “network password”. It´s the same container as for the smb protocol.
Other containers are for the browser “internet password” or web formulars “internet password”.
Until today no credentials were stored in the keychain.