the first thing is to check the communication between the client agent and the OCS server ... For an OCS agent under Windows, edit the file : C:\ProgramData\OCS Inventory NG\Agent\OCSInventory.log
If there is a communication error, it must be indicated in this file.
> If that is right, check the IP address / DNS and port of the server in OCSInventory.ini file (in the same folder).
If you communicate in https, SSL must be enabled and the certificate (shared with the server) must be copied to this folder.
Note : In your case, the service "OCS Inventory service" must be started and if you have to change the contents of the OCSInventory file, you must stop this service first.