I recently noticed that my nextcloud instance was missing photos. I have the android app set to automatically upload my photos. When I need to clear up space on my phone, I make a separate backup (because I’m a paranoid SOB and hard drives are relatively cheap). I noticed that nextcloud auto upload missed about 10% of the photos. I’m not going to bash the nextcloud devs, as I recognize that I am using a free product and am owed nothing, but I’m making this post so others are aware of this risk. Apparently I’m not alone https://help.nextcloud.com/t/android-client-does-not-auto-upload-all-images/216849/14
Can attest that Folder Sync is excellent. I use it all day (in the background) for two-way sync (notes) and backup of photos videos etc
Though a small PSA on setting up:
I once set up a new share on a new phone with two-way sync, and the app decided to sync the (newer) empty directory to the server (i.e. delete everything) instead of pulling the files from the server to the phone.
Easy fix: Restore notes from backup (step 0: have backups in the first place), then do an initial 1-way sync from server to phone, then change the sync job to two-way.