saat masuk ke FTP menemukan error  message
Failed to retrieve directory listing
atau
500 I won't open a connection to your_ip_address
ftp: bind: Address already in use

kemungkinan terjadi permasalahannya karena koneksi 'behind firewall'

solusinya
disable firewall atau coba aktifkan Passive Mode = on

untuk filezilla
* Open Filezilla, go to Edit -> Settings
* Click on Connection -> FTP: Choose Active
* Click on Connection -> FTP -> Active Mode: Select "Ask your operating system for the external IP address"
* Click on Connection -> FTP -> Passive Mode: Choose Fall Back to Active Mode
* Press OK.