IBM RS6000 Service Guide - Page 326

Prevention Strategy The disconnect is caused by the operating system when it initializes the primary console. The tests listed above are conducted with the remote terminal selected as the primary console to manifest the modem's response to DTR transitions. If a local ASCII terminal or a graphics console is to be a permanent part of your server, then make one of them the primary console. Your remote terminal will no longer experience the connection loss. If a local console is not a permanent part of your server, you can still assign either the unused graphics console or the unused serial port as the primary console. This gives you the desired seamless connection at your remote terminal. If you choose to use the unused serial port as the primary console, some initialization traffic will be sent to any serial device attached to that port. As a result, that serial device's connection and function could be affected. These impacts may make that port unattractive for devices other than a temporary local ASCII terminal. D-8 Service Guide