I was using nextcloud at first but kept having sync issues. I use syncthing to sync my Libre office docs and it always disconnects on my Android. I bought Mobious a few months back to sync photos from my iPhone and it always disconnected. So I switched to photosync. So in other words syncthing hasn’t really been reliable for me. I use a free Dropbox account and haven’t had any issues since. And the best thing about Joplin desktop is there is a Backup plugin, so if my Dropbox ever went down, I still have multiple Backups saved locally and on my Proton Drive.