FileZilla Client does not provide a separate “Explicit TLS hostname” or SNI override on the Advanced tab; configure the server’s DNS hostname and explicit FTPS mode on the General tab instead.^1^
Configure FileZilla
- Open FileZilla Client.
- Select File → Site Manager.
- Select the existing site or click New site.
- On the General tab, configure:
- Protocol:
FTP - File Transfer Protocol - Host: the DNS name covered by the server certificate, such as
ftp.contoso.com
Do not use the server’s IP address unless the certificate includes that IP. - Port:
21 - Encryption:
Require explicit FTP over TLS - Logon Type: select the type required by the server.
- User/Password: enter the FTP account credentials.
- Protocol:
- Click Connect.
Explicit FTPS normally starts on port 21 and then negotiates TLS and secondary data-channel ports. Port 990 is associated with legacy implicit FTPS.^2^ FileZilla’s TLS behavior is tied to the hostname configured for the connection rather than a separate Advanced-tab SNI field.^3^
If the certificate prompt names a different server, correct the Host value or install a certificate whose Subject Alternative Name covers the FTP hostname. Do not permanently trust a mismatched certificate merely to bypass the warning.
If the Windows IIS server does not accept explicit FTPS
On the server:
- Open Internet Information Services (IIS) Manager.
- Expand server name → Sites, then select the FTP site.
- Open FTP SSL Settings.
- Select the correct certificate.
- Under SSL Policy, choose:
- Require SSL connections if all clients must use FTPS, or
- Allow SSL connections while testing.
- Click Apply.
IIS supports separate SSL policies for the control and data channels through Custom → Advanced when that distinction is required.^2^
If login succeeds but directory listing times out
That symptom usually concerns the passive FTP data channel rather than the TLS hostname setting. Configure one fixed passive range consistently:
- In IIS Manager, select the server-level node.
- Open FTP Firewall Support.
- Enter a restricted Data Channel Port Range.
- Select the FTP site, open FTP Firewall Support, and enter the firewall’s external IPv4 address where applicable.
- Allow TCP port 21 and the selected passive range through Windows Firewall and any upstream firewall/NAT device.
- Restart Microsoft FTP Service.
Microsoft documents that the passive range must also be permitted by the firewall and that FTPS requires different firewall handling because encrypted FTP traffic cannot be inspected as ordinary FTP.^4^
References