When I try to deploy the iseries_robot to the primary hub I get the following error "Installation packages can be distributed to Nimsoft Server hosts only"
You will need to edit the iseries_robot package in the archive and change the "Group" from installation to application and this will allow you to deploy the package to the primary hub.
Back in the old days, there was a probe called "httpd" which was essentially what service_host has replaced - it hosted the "NMS Server Webpage" where you could download the nimldr, robot packages, hub installer, and so forth. (This is the page that in modern times is displayed by going to http://primary_hub:8080/ )
An "Installation" package is a special type of package in Infrastructure Manager which automatically updates the webpage hosted by the "httpd" probe to contain a link to whatever it is you're deploying to the primary hub (in this case, a new Robot package.)
Since the httpd probe doesn't exist anymore, this is no longer possible - and Installation packages will fail to deploy to an NMS Server without the httpd probe, as seen in the error.