I dont know about kanban but the other stuff can be achieved via webdav. All major webservers can do that or you just use filebrowser.org (a selfhosted webdav server with built-in user management).

I am actually in a clinch with my nextcloud experience and found some different ways to handle this. My plans (tests looks good) is to simply use a small free nextcloud provider just to handle caldav/carddav/notes and stuff without all my data. Just enough to get everything synced.

For my data I plan to use ocis. It's a long year rewrite of owncloud getting rid of PHP and hassle. It's just a single binary. Docker support, too, but it needs some extra steps to initiate, unfortunately. But the experience is fast, modern, clean and simple. Without to much bloat.

Wdym nginx is not supported? It very much is. Nextcloud is a pain to set up but after fiddling with settings for a day or two you can get it working smoothly. In my experience there are no good alternatives to it.

Synology is the answer.