FIX: disconnect printer when reselect same printer

Change-Id: If47a3cfa2409f77dc583922fdb416f93d295f03f
Signed-off-by: Stone Li <stone.li@bambulab.com>

src/slic3r/GUI/DeviceManager.cpp

@@ -3980,6 +3980,7 @@ bool DeviceManager::set_selected_machine(std::string dev_id)
             } else {
                 // lan mode printer reconnect printer
                 if (m_agent) {
+                    m_agent->disconnect_printer();
                     it->second->reset();
                     it->second->connect();
                     it->second->set_lan_mode_connection_state(true);