DAVx⁵
web.de is a German Internet portal which also provides an email service, address books and calendars.
CalDAV/CardDAV setup
Choose "Login with email address" and enter your web.de email address and password.
Password can be your web.de password; or if you use 2-factor authentication you have to generate an app-specific password and use this instead of your normal password
Contact group method: No CardDAV contact group support. Choose "per-contact categories" as contact group method to minimize problems.
Alternatively you can also split CardDAV and CalDAV into 2 accounts.
This can be useful if you use web.de with your own domain for example and/or your email address does not end with @web.de. For this please use Login with Base URL:
For CalDAV, use this base URL: https://caldav.web.de
For CardDAV, use this base URL: https://carddav.web.de
User name: your (web.de) email address
Password: your normal password, or your app-specific password if you use 2-factor auth (see above)
Contact group method: vCard contact groups are not supported. Choose the method used by your other clients or "per-contact categories" to minimize potential problems.
WebDAV setup
You can access your "web.de Online-Speicher" using the DAVx⁵ WebDAV mounts feature.
WebDAV URL: https://webdav.smartdrive.web.de
User name: your email address
Password: your password or your generated app password for Files/WebDAV (when app passwords are active for your account)
Hint: Videos can't be directly streamed due to a limitation of the server