I tried to setup SFTP in Sublime, but the connection failed

I try to set up SFTP in Sublime but it won't connect. I get the the message connection failed, but I don't know why. The password, username host and port are all right.

Does somebody know what the problem is?

{
    // sftp, ftp or ftps
    "type": "ftp",

    "sync_down_on_open": true,
    "sync_same_age": true,

    "host": "host", // host was filled in 
    "user": "username", // username is correct 
    "password": "password", // password was correct
    "port": "21", // also good and I also tried it without port

    "remote_path": "/public_html/name/name/name",

    "connect_timeout": 30,
}