WEBDAV Synology Sync problem

I just setup the Synology WEBDAV Service forwarded all ports and tried it on a second mac to access the Synology webdav and everything works fine. I can create, delete folders. But when I try to create a sync store on the Synology via the webdav service I always get this error…

Bildschirmfoto 2019-01-26 um 14.38.07.png

Any ideas guys?
Thank you very much in advance.

In DEVONthink, hold the Option key and select Help > Report Bug. Thanks

Thx. I’ve sent the bug report.