25. upsd is running, so why can’t I connect to it?

Assuming you haven’t changed the TCP port number on the command line or at compile-time, then you may have some sort of firewall blocking the connection.

upsd listens on TCP port 3493 by default. If you do not specify a LISTEN directive in upsd.conf, upsd only listens on the loopback interface. See the upsd.conf(5) man page for details.