Online accounts / Nextcloud

I can’t log in to my nextcloud account in plasma settings / online accounts. I get the error message “unable to connect to nextcloud at the given server URL”, which is weird because I can log on on another computer running EndeavourOS KDE.
I also can’t log in with Kontact webdav. There I get no error messages, it just won’t sync and the account never appears in calendar/contacts.
I can reach the nextcloud URL with a browser and I can use it with nextcloud-client.

I have installed kaccounts-integration and kaccounts-provider.