FTP, however, operates on two differentTransmission Control Protocolports: 20 and 21.
FTP ports 20 and 21 must both be open on the web connection for successful file transfers.
This is sometimes called thecommandorcontrol portby default.
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Then the client makes another connection to the server over port 20 for file transfers to take place.
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The administrator can change the default port for sending commands and files over FTP.
This blockage may occur on either the server side or the client side.
By default, routers and firewalls might not accept connections on port 21.
UsePort Checkerto scan your data pipe to see if the router has port 21 open.
A feature calledpassive modehelps verify if barriers to port access are present behind a router.
Neglecting to open both ports prevents the full back-and-forth transfer from being made.
FileZillaandWinSCPare twopopular FTP clients.
Both are available free of charge.
