Unable to connect to FTP, get:
Login timeout (300 seconds): closing control connection. Login failed.
The issue can be caused by "poisoned"
mod_delay's cache file
For example, a malicious client might connect, send a
USER command, and then not disconnect for long time. After a few such clients have connected,
mod_delay will add a delay for all clients, such that some legitimate clients may time out. In effect, this may look like a sort of denial of service (DoS).
proftpd.delay file and remove it, usually it located in
/var/proftpd.delay or you can disable
mod_delay by adding the following to your
<IfModule mod_delay.c> DelayEngine off </IfModule>