proftpd-connection lost while uploading

It's most likely an issue with dropped packets to the server. If that's the case, then you'd need to try a different internet connections. Alternatively, you could try switching to pure-ftpd in WHM and see if that helps.

 

if your pure-ftpd is configured to use PAM authentication then you can use this...u will have to create a file named pure-ftpd in /etc/pam.d/ with following entries

#%PAM-1.0

# Sample PAM configuration file for Pure-FTPd.
# Install it in /etc/pam.d/pure-ftpd or add to /etc/pam.conf

auth required pam_listfile.so item=user sense=deny file=/etc/ftpusers onerr=succeed
auth required pam_stack.so service=system-auth
auth required pam_shells.so
auth required pam_nologin.so

account required pam_stack.so service=system-auth

password required pam_stack.so service=system-auth

session required pam_stack.so service=system-auth

---------------------------------------------------------------------------------------