If you have already tried other solutions (see links below), and you your computer is plugged into a switch or a router, either one of these devices may not be forwarding the proper network packets to ensure License Manager is working correct.
One way to identify this is to perform an IPConfig/All at both the License Manager server and the Estimating computer. If the Default Gateway, Subnet Mask, DHCP Server or DNS Servers are different, this is a good indication of the issue. The router may be assigning DHCP information to the computer in question and not forwarding the correct network packets to that computer.