`lftp` does not connect to FTPS (ftp over ssl)

I have trouble in connecting lftp with ftps (ftp over ssl, not sftp!) server (FTP Server Ultimate (PRO version).) running on Android phone.

Technical details:

Linux part.
Following : https://superuser.com/questions/623236/simple-command-to-connect-to-ftps-server-on-linux-command-line
I’ve created following lftp_config file and source it in following way:

$ cat lftps_config 
user photos PASSWORD
set ftps:initial-prot "";
set ftp:ssl-force true;
set ftp:ssl-protect-data true;
set ssl:verify-certificate no;
open ftps://192.168.1.103:43210
$ lftp
lftp :~> source lftps_config 
lftp 192.168.1.103:~> dir
ls at 0 [530 Login incorrect.]

while on “FTP Server Ultimate Pro” logs I see:

2015-10-18 10:10:13 [photosXYZ] - 192.168.1.123 (JBTTAX) - "" and *** are not allowed combination...
2015-10-18 10:10:13 [photosXYZ] - 192.168.1.123 (JBTTAX) New connection...

Could you help me how to setup FTP over SSL (ftps) connection on Linux using lftp (or other command-line tool with good mirror capability) ?

FTR, I use:

$ lftp -v | tail -n 1
Libraries used: Readline 6.3, Expat 2.1.0, GnuTLS 3.4.5, zlib 1.2.8

which according to documentation has FTPS capability (GnuTLS implies it).

For curious, more context:

My final goal: Have some directories automatically backed up (both, locally and remotely) from my Android phone to Linux workstation, laptop etc.

• Android: FTPS server (ftp over ssl, not sftp!), starting automatically when I enter my home wifi, when away using DDNS (Dynamic DNS)
• Linux: lftp (or other command line tool) that backs up stuff from phone – might be triggered by some cron-like automation that in presence of my phone ftps server would trigger automatic backup

Android part I (as least I thought, that I) solved with FTP Server Ultimate (to be specific PRO version).
Server has capability of running FTPS server, and starting it automatically on given SSID or BSSID. When I am travelling it can update DDNS automatically, what makes reachability from my home servers easy.