I am annoyed. How hard can it be to synchronize a file between my #Nextcloud and android phone. Yes synchronize, not auto upload or download. It is supposed to always be the same. In both directions. With a copy on both sides.

The #NextcloudApp is buggy and synchronization still does not seem to be implemented (atleast I could not manage to get it to upload the file to remote after a change). And there is zero open-source apps for #webdav synchronization, if I only want to sync one folder? WTF

Is there anything I am missing?

"2-way-sync" just does not seem to do anything 2-way.
I found #EasySync from F-Droid, but that just Syncs the whole phone.
#DAVx5 does not create a local copy.
FolderSync does not seem to be OpenSource.

So, there is nothing?

@IchMeine
There is absolutely the one and only #syncthing
Once tried, there is no looking back.
@SanskritFritz
The problem is that syncthing needs the software on both sides and does not really synchronise with the nextcloud. So if I do not use my PC for a while and change the file from the smartphone, the version on nextcloud will be outdated compared to the version on my smartphone. I can also not add a new device without access to one of the devices that are currently synchronising.
I would like the file to always be current on nextcloud, with the devices interacting with that.
@IchMeine
Ah so Nextcloud is a must. Then Syncthing won't help you, I agree.

@SanskritFritz
@casraf
@pascalkch

So I think I found my solution. That is not perfectly what I want, but kinda just works ok.

A made a new user on the Nextcloud, just for storing the file/folder.
That users folder gets attached via WebDAV (DAVx5) on my phone.
Synchronization on the PC are handled by the official Nextcloud client.
"Synchronization" in both directions works fine with it now and is very fast.
But: can not access stored file while not connected to the internet with phone.

@IchMeine read but not confirmed myself: the app outside the google-store might work different. Fdroid or other appstores
@pascalkch
I am using the F-Droid-Version and thus it does allow to access the full phone, but sync still does not work after I selected the file.
Thanks for the info though, some might not know.
@IchMeine FolderSync works pretty well for me
@casraf
That is not open-source, or is it?
It seems to also include some Google trackers.
Does the App still work if I disallow all connection that are not to my nextcloud?