I used to use Synology VPN on my NAS (in OpenVPN mode) as an entrypoint into my local network when I’m away from home. This worked fine, up to a few weeks ago - at that point I kept getting AUTH FAILED errors, even though nothing had changed.
I’ve been a user of Dropbox for ages, I’ve tried Owncloud, I’ve tried Box, and probably numerous others that I’ve forgotten about, but in the past year I’ve migrated over to Syncthing, and I haven’t looked back. Opensource software, well designed protocol, complete ownership of your data, I could go on… but this post by gbolo explains it perfectly!