SLES FTP how to restrict user only to the ftp folder

Hello community

I installed a SLES15 SP2 with FTP.

After that i created in the /srv/ftp folder a new folder named work
On this folder i gave the right 730. In this case the specific ftp user which access on this folder can upload files but can not see which files are still uploaded. I created a specific user and assigned it to a group ftpmember. After that i changed the owner of the "work" folder to root ftpmember.
This works fine.
Now the problem is, that when the user logs into the /srv/ftp/work folder, he can also browse to the entire os tree. He doesn't have right to write, but he can see and browse everything. Is there a way to restrict, that the user can walk only ind the /srv/ftp/work folder?

In the vsftpd.conf file I have following entries.

pasv_min_port=30000
pasv_max_port=30100
anon_mkdir_write_enable=NO
anon_root=/srv/ftp
anon_upload_enable=NO
chroot_local_user=NO
ftpd_banner=Welcome on the ftp server
idle_session_timeout=900
local_root=/srv/ftp/work
log_ftp_protocol=YES
max_clients=10
max_per_ip=3
pasv_enable=YES
ssl_tlsv1=YES
xferlog_enable=YES

Some ideas how to solve this?

Thanks in advance for your help
Ramon