diff --git a/src/slic3r/GUI/GUI_App.cpp b/src/slic3r/GUI/GUI_App.cpp
index 04d745a2c74..4dc95102150 100644
--- a/src/slic3r/GUI/GUI_App.cpp
+++ b/src/slic3r/GUI/GUI_App.cpp
@@ -3564,6 +3564,11 @@ void GUI_App::switch_printer_agent()
 
         // Auto-switch MachineObject
         select_machine(effective_agent_id);
+    } else if (effective_agent_id != BBL_PRINTER_AGENT_ID) {
+        // Same agent type but host may have changed (e.g. user→user preset switch between
+        // two Moonraker instances on different ports). select_machine() re-resolves the host
+        // from the current preset and reconnects if the MachineObject differs.
+        select_machine(effective_agent_id);
     }
 }