I hope all is well. Let me see what we can do to help straighten this out for you and get you back on track.
Just clarify for me, if you could please, what you mean by
client version? do you mean the SCCM agent software?
If so, the answer is
maybe, depending on what you are looking to do with it.
For example, if you are looking to have SCCM monitor itself, then the answer is yes, it would need the agent software installed. The same would be true if you wanted the SCCM server to deploy software to itself, or software updates as well.
If however, you wanted to stage the client agent to be deployed as a package from the server to other client endpoints that will be managed by the SCCM server, then you
WOULD NOT need to have the client agent software installed on the SCCM server, but rather you would need to have the client software agent package installation available to be deployed by the SCCM server.
Let me know what you are thinking based on what I outlined above, and then we can discuss any issues you have from there,
definitely recommend that you look at separating some of those roles onto different servers, as you have a
massive SPOF (Single Point of Failure) issue waiting to blow up on you, not to mention performance concerns, with everything running in one box.