Quick answer: FTP/SFTP issues: use SFTP port 22, passive mode in FileZilla, copy credentials exactly from Plesk.
If you landed here: FileZilla shows "Connection timed out", "530 Login failed" or "Could not connect to server".
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Frequently asked questions (FAQ)
FTP connection timeout – what to check?
Host = domain or server IP, port 21 (FTP) or 22 (SFTP), enable passive mode in FileZilla, copy credentials from Plesk.
FTP or SFTP – which is better?
SFTP (port 22) is more secure and standard on NexoraHost/Plesk. FTP (port 21) only if explicitly needed.
530 Login authentication failed?
Username = full email or FTP user from Plesk. Reset password. No spaces when copy-pasting.