Fawn box - FTP behavior is inconsistent

Trying to pwn the fawn box.

Using OpenVPN + starting point. Also using VM with parrotOS installed.

FTP’d into the target machine.
Entered username anonymous and email as password.
Get the success message.

Then if I type ANY command I get this

425 Failed to establish connection.

Doesn’t matter what the command is - LS, DIR, GET FLAG.TXT - I get the same error message.

Screen log:

└──╼ $ftp
Connected to
220 (vsFTPd 3.0.3)
Name ( anonymous
331 Please specify the password.
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> get flag.txt
local: flag.txt remote: flag.txt
200 PORT command successful. Consider using PASV.
425 Failed to establish connection.

So I’m apparently connected - but it failed to establish connection at the same time. This is inconsistent.