Did you try out Nextcloud AIO instead of setting it up manually?
I agree that NC has a lot of problems. It’s a good example of an application that tries to do everything and unsurprisingly doesn’t do many things truly well. With that said, I was surprised that NC AIO ran well for me despite the horror stories of NC I’d always read. I’ll keep using it for now, but I could easily switch back to using Resilio Sync, File Browser, and Photoprism.
My main problems with Syncthing is that there’s no official iOS client and that there’s no easy selective sync (Resilio can do this) - using ignorelists gets annoying if you’ve got a large folder structure and many files/folders that you selectively need to sync.