After setting up a SFTP only chroot jail I had to log with Filezilla and got error: Error: Server unexpectedly closed network connection Error: Unable to connect to server
The set up was working previously so I had no idea what was going on. In those cases, just check your logs: nano /var/log/auth.log
In my case, I found this pesky line: fatal: bad ownership or modes for chroot directory "/srv/www/a-domain.com/public_html"
To check what
chroot a user has:
nano /etc/passwd <= we hav a a list of all users and its home directory.
The structure has to be so that the user's
chroot has to be owned by root and not writable by the group.