Although most lftp versions work with default configurations, some users have reported the following generic error during TLS negotiation.
gnutls_handshake: A TLS packet with unexpected length was received.
If you encounter this error, it can generally be resolved with the following explicit configuration parameter:
lftp -e "set ftp:ssl-auth TLS;set ftp:ssl-force true;set ftp:ssl-protect-data true;" ftp.foldergrid.com