The DebugServer is a Sun RPC server that is registered with the rpcbind server. When you require more than one debug server to run on the same host, assign a unique slot number (in the range 0..65535) to each of them so that individual debug servers can be identified. If only one debug server is started on a given host, it is not necessary to allocate a slot number as 0 will be used by default.
If you decide to assign a slot number to your DebugServer, use the DebugServer environment variable CHSERVER_HOST.