KRDC Gives Error for IP Local IP Address?

I'm using KDE's Remote Desktop Client (KDRC) to connect to a computer in the basement.

Here is the output of ip a on the terminal downstairs.

These appear to be addresses on the private network. None of them work in the KDRC window. They all bounce back with an error message saying server not found.

I'm inexperienced with KRDC. Is this an error on my part? Is there something I'm missing (Set up before connecting to the desktop downstairs?)

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