From the WU-FTPD FAQ page (
http://www.wu-ftpd.org/wu-ftpd-faq.html#QA78)
# ftpd stops accepting connections when a lot of connections come in.
This is a feature of inetd, not ftpd. Inetd will limit the amount of connections that can be made to a service per minute. Some versions allow to specify this amount in inetd.conf, by specifying it in the nowait flag, like :
ftp stream tcp nowait.256 root /usr/sbin/ftpd ftpd -a
which will allow 256 connections per minute. Check the manpage for inetd.
