Update: This fix was finally merged into php 5.6 and 7.0 in Dec. of 2015. It had 165 votes! Thank you for support.
Setting up an FTPS server securly is a big pain. If your environment is behind a NAT, sometimes the server doesn't even know what its public address is, which makes enabling PASV mode fun!
I'm trying to connect to a server setup like this and when I enable PASV mode, it responds with an unroutable internal address.
FileZilla works around this issue by ignoring the address and using the servers inital address instead and everything works as expected.
PHP's FTP library does not. It happily accepts the unroutable address and ultimately fails to connect moments later.
This guy knows what I'm talking about and actually patched php to fix this bug.
If you have a moment, please vote this bug up so it makes it into php's next offical release.
It was reported in 2011 in version 5.3 and is still unassigned.