Clients are windows and/or linux?
Windows => stop ocs service, edit c:\programdata\ocs inventory ng\agent\ocsinventory.ini file. Change the variable server= to http[s]://fqdn_or_ip/ocsinventory. Save. Restart ocs service
Linux => ocs agent installed with apt, edit /etc/ocsinventory/ocsinventory-agent.cfg file. Installed manually, edit /etc/ocsinventory-agent/ocsinventory-agent.cfg file. In both cases change "server=" to http[s]://fqdn_or_ip/ocsinventory. Save and launch an inventory.
Regards
Frank