If you are not able to connect to another Windows machine using Remote Desktop inside of a local area network, the following troubleshooting steps may prove useful:
Ensure that there is not a general network connectivity problem using commands such as ping and ipconfig.
Ensure that Remote Desktop is enabled on the destination machine.
For detailed information on the steps required, see Enable Remote Desktop on Microsoft TechNet.
Verify that the appropriate users and groups are in the Remote Desktop Users group on the destination machine.
Use the Dell Troubleshooting Tool to verify that the required ports are open between the two systems.
Turn off the Windows Firewall on the destination system temporarily. In rare cases, it may be necessary to turn off the firewall on the source machine also.
If these troubleshooting steps do not resolve the issue, review the event logs on the source and destination systems for additional information to help determine the scope of the problem.
For additional troubleshooting, reference the following Microsoft article: Troubleshoot Remote Desktop problems.
Review recent Windows Updates that may have resulted in network-related changes.
Review the network bindings and provider order.
Use the troubleshooting tool from step 4 to connect to switches and routers to see if there is a network blockage.
Try connecting to the destination machine's IP address instead of its name. If you can connect using the IP address and not the name, there is likely a problem with DNS resolution.
Verify the version of the Remote Desktop client is compatible with the server or client you are connecting to.
Disable third-party antivirus/security software that may be blocking communication.
Review the Microsoft KB article How to Change the Listening Port for Remote Desktop to determine whether the listening port has been changed on the destination machine.
In rare circumstances, the TCP stack may be corrupt, requiring a reset.