Hallo,
ich würde einmal diese Sachen prüfen:

1)Open Operations Navigator, and right-click on the name of the iSeries or AS/400e server. Select Properties, and click on the Connection tab. If the Performance area is set to never look up the IP address of the iSeries server and an IP address is specified, verify that it is the correct IP address for the iSeries server.


2) Cause
The address used for the server was found, but the connection to the server timed out.
Recovery
Make sure TCP/IP has been started on that server, and that the host servers have been started. If this does not fix the problem, verify that the IP address used to attempt the connection is correct for the server. This address is logged in a previous message.
Verify TCP/IP address servers (Domain Name Servers) are configured correctly on this PC and have the correct address for this server. If the address is correct, check the HOSTS file on your computer for errors. If the IP address specified in the HOSTS file is incorrect for the server, correct it and try the operation again.
If a TCP/IP router of some kind exists on the network between the PC and the server, make sure the router is configured to allow connections to the iSeries Access host servers and to the Server Mapper on the server.