because this 4g / 3g usb modem is not recognized. but gives me a tethering connection? is there anything I can do?

thank you

The modem works as tethering so if you can use the Internet, you are set up correctly.

therefore it is not configured as a modem.

Do I have to change the USB pen to manage it as a modem?

Type Huawei E3372? so you can see the 4G signal?

or do you recommend a better USB modem?

E3372 should work as tethering as well.

Why you want to use as a serial modem? Compatiblity is difficult.