Have you tried the inetd service. inetd should be running for ftp to be use. I had a problem: I could not ftp or telnet my qnx pc on network. I enabled inetd service (QNX did not start inetd by default). As soon as I did it everything worked fine. Ofcourse the lines for ftp and telnet should be uncommented in /etc/services file. In addition check
whether the permissions for users are there
Relevant users have been added to allow ftp use (user accounts are there too).
by the way telnet is on port 23 and ftp on 21 by default in services file.
telnetd/ftpd are written in such way that you can not “just started”. They expect being started by “inetd”, so yeah, check out “inetd” and “/etc/inetd.conf”.