Resolution:
When the LCN provided in the server_names argument is not fully qualified rtadmin is not sure if NODE_NAME is a protocol or a machine name so it attempts to load the file node_name.dll when stoping an RTserver

When rtadmin attempts to stop an RTserver with the argument node_name  (rtserver –stop -server_names NODE_NAME) it tries to load a nonexistent DLL with the filename “ NODE_NAME.dll “

Failed to load shared library 'tipcld_NODE_NAME_50.dll'.

This can be seen in the rtserver trace_file of the remote RTserver where the command
        rtserver –stop -server_names NODE_NAME
is initiated from. This has been reported in CR 1-6QBWXB for ss 6.7.0 .  . A fix date is TBA

To avoid seeing this message use fully qualified LCNs as in the following example:
       rtserver -stop -server_names tcp:NODE_NAME:5101