Synology DSM

DAVx⁵ has been successfully tested with Synology DSM.

Synology DiskStation Manager (DSM) is a Linux based software package that is the operating system for Synology's DiskStation and RackStation products. A CalDAV server is available in the base system. CardDAV can be installed as an extra package.

On many Synology systems, it's also possible to run other CalDAV/CardDAV software using Docker or virtual machines. In this case, see the respective configuration pages for details.

Packages

There are various Synology packages you can install and use with DAVx⁵ (and other CalDAV/CardDAV clients). It's important to know which packages you are using to determine the correct base URL.

Protocol Package Notes
CalDAV Synology Calendar Recommended for CalDAV
CalDAV WebDAV Server Not recommended for CalDAV! Since version 2.4, WebDAV server doesn't support CalDAV anymore.
CardDAV Synology Contacts Recommended for CardDAV
CardDAV CardDAV Server Alternative for CardDAV (not recommended for new setups)
WebDAV WebDAV Server Recommended for file access (not for CalDAV!)

For every package, there is a different base URL; see specific instructions for each package below.

Hint: Synology locks out certain IP addresses if you try to log-in wrongly for a few times. In this case, have a look in your DSM in: Control panel / Security / Account / Click the "Authorize/lock" button / List of locked addresses. Select the blocked address and remove it from the list.

Synology Calendar

The Synology Calendar provides a calendar with Web and CalDAV interface. You can view the CalDAV URL in the Calendar Web interface (Calendar > CalDAV Account). Use the macOS / iOS URL.

So, the CalDAV Base URL could look like this:
http://diskstation.lan:5000/caldav/YOUR_USERNAME or
https://diskstation.lan:5001/caldav/YOUR_USERNAME with HTTPS;

or if you're using LDAP try:

http(s)://domain:port/caldav/user@LDAP.domain

Notes:

  • You can also use port 38003 (HTTP) or 38443 (HTTPS). You may also have to additionally open these ports when you need CalDAV access from outside.
  • The Calendar package seems to provide a CardDAV service, too. This is why "CardDAV" appears in DAVx⁵ accounts created for Synology Calendar. You can even create an address book using DAVx⁵. However, this feature is not officially supported and there's no user interface in the Calendar package. So, use the CardDAV server or Synology Contacts instead (see below).

See also: Synology KB: How can I sync Synology Calendar with CalDAV clients?

Synology Contacts

Synology Contacts provides a CardDAV server and a Web interface for address books. It supports shared address books.

Take the CardDAV base URL from the Web interface: Address book / CardDAV / MacOS/iOS URL. It should look like this:

http://diskstation.example:5000/carddav/Username/ (see screenshots), or
https://diskstation.example:5001/carddav/Username/ with HTTPS

CardDAV Server

The CardDAV Server provides a CardDAV server with a Web interface for the address book.

CardDAV Base URL: http(s)://example.com:port/addressbooks/users/YOUR_USERNAME
(for example: https://diskstation.example.com:8443/addressbooks/users/sample if your user name is sample)

or if you're using LDAP try:

https://domain/addressbooks/users/user@LDAP.domain

For older versions of CardDAV server, you need to append addressbook like that:
http(s)://example.com:port/addressbooks/users/YOUR_USERNAME/addressbook

User name and password: same as for Synology DSM

Contact group method: groups are separate VCards

Do not import .vcf files generated by Android directly into the Synology CardDAV server! It often breaks synchronization (500 Internal server error), because Android exports vCard 2 files, and Synology will import these files without error message but they can't be processed later (because CardDAV requires vCard 3). Import them on Android instead.

WebDAV server

You can mount folders from the Synology WebDAV server using the DAVx⁵ WebDAV mounts feature.

WebDAV URL: http://diskstation.example:5005/ (adapt protocol, host name and port accordingly)

WebDAV server for CalDAV (legacy)

If possible, use the newer Calendar package instead of the outdated CalDAV function of the WebDAV Server (which doesn't seem to be maintained anymore) package to avoid problems.

If you're still using the WebDAV Server package for CalDAV (which is not recommended):

  1. Open Synology DSM: Control Panel / WebDAV.
  2. Enable WebDAV or WebDAV HTTPS and remember the port (5005 in the screenshot).
  3. Enable CalDAV in the WebDAV server package.
  4. Go to "View calendar list" and add a calendar. Make sure that you have read/write permissions on the destination folder.
  5. In the calendar list, each calendar has a location (e.g. SomeFolder in the screenshot). This location is required to add the calendar with DAVx⁵. You can omit the last directory level (TestCalendar in the screenshot), because DAVx⁵ will enumerate all calendars in the given folder.

Now you can add an account in DAVx⁵:

CalDAV base URL: http(s)://diskstation.example:5005/test/SomeFolder

Known issues (can both be worked around by using the Calendar package instead of the WebDAV Server package for CalDAV):

  • If you're accessing an empty calendar (for instance, because it has just been created), Synology returns 404 Not Found when this collection is queried. To work around this, add an event and a task to the calendar. Then synchronize and the 404 error should be gone. (Synology support ticket 2530270)
  • When there are timezone definitions that contain TZOFFSETFROM:+005730 (0 h, 57 min, 30 s), the server will return invalid time zones with TZOFFSETFROM:+5730 (57 h) on REPORT multi-get requests (but not GET requests). This can prevent events from being parsed and cause an "invalid iCalendar exception" with "Zone offset hours not in valid range". (Synology support ticket 2532591)