The function set-remote-debugging-connection sets an enabling switch controlling which remote debugging connection will be used by the remote debugging interface (entering the debugger, start-remote-listener or remote-inspect) on the client side.
If connection is t, then the default connection will be used (which may be set by set-default-remote-debugging-connection, start-client-remote-debugging-server, or configure-remote-debugging-spec). If connection is an instance of client-remote-debugging, then connection itself will be used. If connection is nil, then no connection is specified (the API may open one when needed).
The setting is global, unless it is called within the dynamic extent of with-remote-debugging-connection, in which case its effects last until the exit from this extent.
When entering the debugger, the connection is used when invoke-debugger is called and no hook blocks it. Possible hooks include *debugger-hook* and with-debugger-wrapper. For the Remote Listener and Inspector, the functions start-remote-listener and remote-inspect use the connection.
In typical usage, you will not need to explicitly call set-default-remote-debugging-connection, because start-client-remote-debugging-server and configure-remote-debugging-spec (with the default parameters) both set the default connection.
In all cases, if the debugger is invoked and there is no connection to use, LispWorks may open a connection if it was configured to do so by configure-remote-debugging-spec or with-remote-debugging-spec.
You can obtain a client remote debugging connection by using the :open-callback keyword with start-client-remote-debugging-server or configure-remote-debugging-spec.
with-remote-debugging-connection
set-default-remote-debugging-connection
start-client-remote-debugging-server
configure-remote-debugging-spec
Remote debugging
LispWorks User Guide and Reference Manual - 20 Sep 2017