In the first example curl works with ftp and --ssl and -k. The -k ignores the certificate which whilst it works is not ideal.
You can see from the second example below that curl does not work using ftps.
curl is trying to use port 990 which would normally mean it is attempting 'implicit FTP over TLS' rather than 'explicit FTP over TLS'
Port 990 is open on the firewall.
Filezilla only presents the certificate the first time for a set of credentials (unless you don't accept the certificate).
The certificate is valid btw.
The site expects TLS 1.2 minimum with explicit FTP over TLS.
We use *web/ftp to upload the license files and the end user is downloading the file.
C:\HIT\PVX>curl --ssl -k -O
ftp://ftp.hit.net.au/public_html/Future/Texts/0030020.txt --user xxxxxx:xxxxxxxxxxxxx
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 66 100 66 0 0 86 0 --:--:-- --:--:-- --:--:-- 86
C:\HIT\PVX>curl -O
ftps://ftp.hit.net.au/public_html/Future/Texts/0030020.txt --user xxxxxx:xxxxxxxxxxxxx
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- 0:00:20 --:--:-- 0curl: (7) Failed to connect to ftp.hit.net.au port 990: Timed out