A client with name "..." is already connected and unknown screen name

In the server configuration, there was already a PC (named Anthony-PC, the one im using as a server) in the centre box which i assumed was the server with anything else added being the clients. So I add a client next to it and apply the settings.

On my server PC, it keeps showing the error:

WARNING: a client with name "Anthony-PC" is already connected
NOTE: disconnecting client "Anthony-PC"
NOTE: client "Anthony-PC" has disconnected

and on my client PC the error showed up as:

ERROR: server already has a connected client with the name "Anthony-PC"
WARNING: failed to connect to server: server already has a connected client with our name

and just to be sure, my client PC is not called "Anthony-PC", only my server PC is.
I tried taking out the centre PC from the configuration when I thought that was considered a client, leaving behind just the client and it showed up as

FATAL: unknown screen name `Anthony-PC'

with the client pc's error being:
WARNING: failed to connect to server: Connection was refused