I have configured a FileZilla FTP Server on my Windows 7 Professional PC and some clients download files with different accounts. Everything works with other Windows clients and even a test with my Mac OS 10.13 worked, but a client with a newer Mac version is unable to login. He inserts the FTP link in Safari and it opens Finder (until this it's OK because I've done it on my Mac), but then it loads for a long time and says "A problem occurred during connection. Check your username, password, and server IP address." We've tried both "registered user" and anonymous login.
Unfortunately I don't have the phisical machine available to me so I was wondering if it could be that new Macs don't support standard FTP without SSL, TLS or SFTP? However I tried to set "Force SSL" on FileZilla server, but it got worse because then Mac said that the password was wrong.