How to connect to FTPS or mount it to local folder
FTPS - is FTP with SSL layer, please don't mess it with SFTP. FTPS uses regular FTP protocol underneath, but all commands and data is encrypted using SSL. So mechanism of work is pretty same as in HTTPS: old protocol encapsulated in security layer. But that's breaks a lot of traditional FTP clients you are used to.
So here is 2 dead simple solutions I've tested with many FTPS servers, which setup could be much more correct then it actualy was. You can encounter FTPS servers configured in 2 ways with ports 20 + 21 and 989 + 990 used.
Filezilla is a GUI client available for both linux and windows. It has pretty specific interface. It can correctly handle wrong certificates, unusual ports and so on. Can be downloaded here. Just enter host, username, password and port(only if needed) and press Connect.
Mounting FTPS under linux
There is a an utililty called curlftpfs. It works under linux/*bsd and allows to mount remote FTPS(S) dir to you local directory. So in the simpliest ways on the ubuntu/debian it will look like:
sudo apt install curlftpfs
curlftpfs -o ssl ftp://USERNAME:PASSWORD@HOSTNAME:21/ /tmp/ftp-mount
If server you connecting to has wrong or outdated SSL certificate you can try:
curlftpfs -o ssl,no_verify_peer,no_verify_hostname ftp://USERNAME:PASSWORD@HOSTNAME:21/ /tmp/ftp-mount
Remember, you can change port only in connection string, maybe via .netrc, but NOT with curlftpfs ftp_port option.
If you know a solution that allows to mount ftps folders under Windows, please mention it in comments.