As a good security practice, it's better to have vsftpd run as a non-privileged user rather than as root. By default, it wants to run as user 'ftp', but the configuration that comes from the optware install uses 'ftpsecure' (see the nopriv_user setting in the configuration file). You should add this username to /etc/passwd. Make sure to select a unique user id (in this example, the UID is 104):
This created user - "ftpsecure". How about its password?
When using FileZilla, what server type to use? FTP/SFTP/FTPS/FTPES?
What transfer speed are you getting after vsftpd installed in MBWE? Thx