Make sure the client computer is connected to the network and turned on and that it is not powered off by energy saving software. Retrospect can not wake up a sleeping client computer in most cases. Try a simple restart of the client computer.
If it is a mobile computer make sure it has not been "suspended" or put into "sleep" mode. (Restart a suspended Windows computer to let Retrospect see it.)
Make sure the client has the most recent version of the Retrospect client software and that the client software loads at startup. Open the Retrospect Client Control Panel. It should display a status of "Ready" or "Waiting for first access".
Test the connection between the backup computer and the client. Go to Configure > Clients (or Sources). Select the Client and click Properties, then click Refresh. Macintosh users can go to Sources, select the client and click Refresh. This will force a connection to the client. If it can connect with the client, Retrospect displays the measured transfer rate in kilobytes per second. Also try pinging the client from the command line.
Turn off any firewall software on the client and backup computer and attempt the connection test again in step 4. Your Firewall must be open to port 497 to allow UDP and TCP traffic.
Last Update: February 13, 2012