If your desktop and laptop are members of different subnets, you may need to add routes so that those devices can find each other. For example, if your wireless LAN uses 192.168.1.0/24 and your Ethernet LAN uses 192.168.2.0/24, you may need to add a route to your laptop to reach 192.168.2.0/24 through your router (e.g., "route add 192.168.2.0 mask 255.255.255.0 192.168.1.1 metric 2"). Enter the opposite route on your desktop to reach 192.168.1.0/24. Your router may also have a configuration option that must be set to permit traffic between LAN stations.
You can verify connectivity between your desktop and laptop by using the "ping" command. On Windows, open a Command Prompt window and type "ping <his IP address>". If the desktop and laptop cannot ping each other, they cannot share files. If they can ping each other but still cannot share files, work on configuring the Windows Workgroup correctly. To diagnose Windows Network Neighborhood problems, use the Windows "nbtstat" and "net" commands.
This was first published in December 2004