ZyXEL Communications Prestige 28641 - Manual (Page 132)

118 Telnet Configuration and Capabilities
menu 1, telnet will still be available provided you assign the Prestige
an IP address.
Telnet Capabilities
Single Administrator
To prevent confusion and discrepancy on the configuration, Prestige will
only allow one terminal connection at any time. Prestige also gives
priority to the RS-232 connection over telnet. If you have already
connected to the Prestige via telnet, you will be logged out if
another user is connecting to the Prestige via the RS-232 cable. Only
after the other administrator has been disconnected will you be able to
telnet
to the Prestige again.
System Timeout
When you are connected to the Prestige via telnet, there is a
system timeout of 5 minutes (300 seconds). If you are not configuring
the device and leave it inactive for this timeout period, then the Prestige
will automatically disconnect you.