Environments
Server configuration
Device: applicable to all
Issue
I cannot establish an FTP connection from my device.
Is it possible to use "active" mode when establishing connections to FTP servers?
Solution
Make sure FTP servers are set up in "Passive" mode for the device to establish a connection.
Cause
Onomondo network uses device first communication (does not allow a server to initiate communication with a device) and NATing of SIM IP addresses when data enters the Internet from a device (also considered the client) using Onomondo SIMs.
As a result, the FTP server will be unable to initiate the data connection between itself and the client because of the internal IP address / port provided by the client (which the FTP server cannot find outside the network), and because the firewall on the Onomondo network will block any server's first connection attempt.