To establish a data connection for a tệp tin transfer or a directory listing, an FTP client (in the passive FTP mode) sends PASV command lớn the server. The server responds with its IP address and port number. The client should connect lớn that IP/port lớn initiate the transfer.
It's quite common though that the FTP server is behind a NAT. And it's aware of its local address within its NATted network only. When it reports such IP address lớn a client outside the NAT, the IP address is obviously of little use. It's clearly a misconfiguration of the FTP server. The FTP server must report its external IP address, that can be used outside the NATted networks.
As this is unfortunately a common issue, many FTP clients try lớn detect this (by checking that the reported IP address is within the range of addresses reserved for local communications within a private network). FileZilla does too and reports the mentioned message. You should see the offending address in the FileZilla log:
2017-04-05 08:02:00 12064 3 Command: PASV
2017-04-05 08:02:00 12064 3 Response: 227 Entering Passive Mode (10,0,0,1,213,36).
When encountering this, FileZilla tries lớn connect lớn the primary address of the FTP server instead, as that is usually the correct address lớn use. So in most cases, you won't notice the problem at all.
Though as you mention that "Browsing is nearly impossible", it looks lượt thích that it does not help. If that's the case, most usual problem is that some firewall (or the NAT) on the way between you and the server blocks the connection attempt lớn the data port (as reported in the response lớn the PASV command).
See my article about Network configuration for FTP passive mode for details.