> Sadly for the general Dropbox replacement I haven't found anything either.
I had really good luck with Seafile[0]. It's not a full groupware solution, just primarily a really good file syncing/Dropbox solution.
Upsides are everything worked reliably for me, it was much faster, does chunk-level deduplication and some other things, has native apps for everything, is supported by rclone, has a fuse mount option, supports mounting as a "virtual drive" on Windows, supports publicly sharing files, shared "drives", end-to-end encryption, and practically everything else I'd want out of "file syncing solution".
The only thing I didn't like about it is that it stores all of your data as, essentially, opaque chunks on disk that are pieced together using the data in the database. This is how it achieves the performance, deduplication, and other things I _liked_. However it made me a little nervous that I would have a tough time extracting my data if anything went horribly wrong. I took backups. Nothing ever went horribly wrong over 4 or 5 years of running it. I only stopped because I shelved a lot of my self-hosting for a bit.
[0]: https://www.seafile.com/en/home/