The server's license file contains the machine's hostname or fully qualified domain name (FQDN), put there by the FLU at the time the license is installed. If the machine's hostname or FQDN changes after the license is installed, then the license manager will not be able to resolve the name in the file with the new name and therefore it will not be able determine it is properly and uniquely a part of the network it serves.
The server's license file contains its hostname or FQDN and the client machine licenses normally also have the same server name in their license files.
If you changed the server's hostname or FQDN, then you will need to edit the license files (in plain text) to update the name.
Running, saving, and reviewing our license diagnostic will tell you where the server name appears in license files.
To get diagnostics from our Foundry License Utility (FLU)
click on "Diagnostics" then
"Run Diagnostics" then
"Save" the output as a file.
The server's new name will appear at the top of the server's diagnostic.
After fixing the files, you should use the FLU to STOP and then START both the RLM and the FLEXlm servers.
If you need help fixing the license files, just send us a diagnostic from the server and from one of the clients.