COM10 is usually the upload/debug port, while COM11 might be the Modbus RTU serial port (if you're using RS485) or a Virtual COM for Modbus TCP, depending on your setup.
Check Device Manager after the reset and download. Label or match the COM ports with what the IDE and system are detecting.
Make sure no other app (like Arduino IDE or serial monitor) is connected to either COM port while using PLC IDE.