000 Your session has timed out.
closedNo commands have been sent for 300 seconds - Disconnected
http://scott.free-bsd.org/protocol.html
You may have to modify the _update() function in the dyndns.class to get an accurate error message.
e.g. add
log_error("phpDynDNS: Return Code: {$this->con['buffer']['all']}");
after
$code = substr($this->con['buffer']['all'], 0, 3);
but make sure to remove that line again when you have the error mesage.