syncthing and webdav on NAS

I store data with nextcloud on a managed server. There are users outside accessing the nextcloud-data. My own devices (PCs, Laptops and NAS) are synced with Syncthing. I need a “connection” between my devices and Nextcloud. If there were a nextcloud-client for the NAS (qnap), my problem would be solved. But there is no such client. So I try to use the NAS as “gatway” between nextcloud and my devices: The Nextcloud is mounted on NAS using Webdav, and the Webdav-Directory on NAS should be synced to my other devices using Syncthing . Unfortunately, even so data on NAS are shown identical to Nextcloud, no synchronization to the other devices (my PCs and Laptops) happens. There is no error message. (otherwise Syncthing works well on the NAS) NB: I do not use the nextcloud client on my devices to avoid race-condition with syncthing. I should also say that there is a special constellation: The webdav-next folder on NAS is synced to a next-folder on PCs and Laptops. But these next-folders are also synced to an further independant next-directory on the NAS (a sort of Y-configuration). Does anyone see the problem?

I have a naive question, since I have not used WebDAV in so long: when you mount a WebDAV location to a local directory, the files you see are not actually on your local disk, are they? I think files are listed but only downloaded on demand. If that is the case, it would explain why Syncthing does not sync any files, because it does not detect any.

Hi anaqreon. Mounts are usually not a problem for Syncthing. For example, I use encfs for mounting encrypted files and syncthing works well. So, a webdav-mount (remote-mount) would be treated differently? In my case, files are even locally cached…

EncFS and WebDAV mounts are two very different types of filesystems, with the former being a type of loopback filesystem while the latter is a network filesystem.

The underlying network transport for WebDAV is HTTP, so files are uploaded/downloaded on-demand. Filesystem notification isn’t available so Syncthing’s file watching feature won’t work, requiring that changes be detected only during rescans.

Depending on the WebDAV client, their may or may not be caching. And even if there is caching, the file listing seen in a file manager is virtual – it’s a representation of what could be on the NAS, but not what’s physically on the NAS.

Without more details about the setup, including screenshots of Syncthing’s UI with panel details visible, and other info, it’s impossible to diagnose properly.

Also, for usual setups, it helps a lot to post a diagram (even if it’s a photo of a pencil drawing) so that anyone reading the post can better understand the various connections involved.

Ok, I see. QNAP has a built-in app called HybridSyncBackup HBS3. This app offers the possibility to install one- and two-way sync with webdav-servers. It is not inode-triggerd and therefore not realtime. It must be configured to sync periodically. It’s not perfect, but it is the best available option. And Syncthing on Qnap will then sync to the different PCs and Laptops. Thank to everybody, your answers were helpfull. Fabio