A message time out error typically occurs with a CORIOmaster with the CORIOgrapher software via Ethernet for one of two reasons -- the PC is on a different subnet as the CORIOmaster or another device is already logged into the CORIOmaster.
To test the network, simply open a command prompt and ping the discovered IP address of the CORIOmaster. If the address is unreachable, then this means that the PC may have a physical connection to the CORIOmaster, but the network settings are not in the same IP range.
If the IP address can be pinged successfully, then this usually indicates that something else is logged into the CORIOmaster. This is usually a control system that stays logged in at all time or leaves the port open. Logging out the control system or disconnecting it physically will usually allow login via CORIOgrapher.
Please not that if the controller is physically disconnected, the CORIOmaster will not disconnect the user until the user timeout period has elapsed. The default timeout period is five minutes, although this time may be longer depending if the setting has been changed. It is also possible to for the timeout to be disabled entirely. If this is the case, then it may be necessary to reboot the CORIOmaster to free up the connection port.