Please no. The mistake should be fixed in the misconfigured FTP server, not in ftplib, which should not make this event pass unnoticed or take arbitrary decisions. Filezilla is different than ftplib in that it's an end-user app. ftplib is not (e.g. it can be used for testing FTP server implementations, like pyftpdlib).

A possible alternative is making socket.create_connection() show the address in case of error, like we do in socket.create_server:
https://github.com/python/cpython/blob/8702b67dad62a9084f6c1823dce10653743667c8/Lib/socket.py#L803-L805
That would at least provide a hint on what's the real issue. If you want to provide a patch for that you have my blessing.