Discovering Physical Windows Servers using EHI Agent under DMZ

We have few Windows Physical Servers under DMZ where all the Non-Standard and Unused ports are blocked. We got the agents successfully installed on the DMZ Servers but unable to connect. We are using Port 7988 for EHI Discovery, is it enough to just open this port between the Collector Server and the DMZ Windows Physical Server or are there any other ports that needs to be added under Firewall rules for the discovery and data collection to be successful. Thanks