Another vote for syncthing. I have Synology home NAS, Syncthing in Docker on NAS, Tailscale on both Synology and my laptop so the IP address of the server is always the same, and it works way better than either Dropbox, OneDrive or Synology's own SynologyDrive.

What’s wrong with Synology Drive?

It’s working just fine for me.

Definitely syncthing - it's incredible. I have all my files managed with it, bare git repositories managed with it, a common shared folder with my partner, my android phone auto uploads photos etc.

It all truly just works and it works well.

I’ve used syncthing for years now to keep a bunch of large folders with millions of files synced between multiple computers running windows, linux and macos. Works really well and it is light on system resources.