As the RSN.ini provides the Revit application workstation which Hosts are visible during file navigation, as well as determines which Hosts can be accessed through the Revit Server Administrator from an Admin Server, it is one of the more important files in the Revit Server Network.
We have seen that even though the RSN.ini is in the proper location, the workstation cannot see any Host Servers in the Revit Server Network, or the Admin Server cannot access Host Servers through Revit Server Admin.
In a few of these cases, the issue was that in certain environments, Windows hides the file extension for known file types, Text documents being one of them.
Therefore, a user may think they have created an RSN.ini file, when in reality they have created an RSN.ini.txt file, which Revit does not recognize.
The fix is to make sure the Type for the RSN.ini says "Configuration" as in the screenshot above.
To have Windows show the file extensions go to Control Panel > Folder Options > View > Advanced Settings then make sure "Hide extensions for known file types" is unchecked, as in the screenshot below: