tcp port always closed in inetd

sco unix 5.0.x, several weeks ago, I add a telnet-like service in inetd.conf, it runs well for 100 network terminals.

But nowdays, the terminals can connect to server successfully after booting machine, but several hours later, can not connect. "netstat -p tcp -a" can NOT find the port in LISTENING state. If I "kill -1 pid-of-inetd" to refresh the inetd process, the port listens again and terminals can connect too. But hours later problem occurs again.

why and how to solve it?

Put the service entry in inetd.conf to begining of file?

inetd daemon will automatically close the service port if there are more than N connections in a miniute requesting the service. The default N on linux is 40 and can be adjusted. But I find nowhere to adjust it on sco.