If have the AP set to 3G/4G Mode.

I plugged in the USB Modem, it´s identifing, and shortly done correctly, try connecting, and then give me the message, it´s unplugged.

Hast anyone the USB Modem running?

On my old TPlink Router 3020N, this USB stick works fine.

So, it´s strange, that a much older AP from TPlink is working with this stick.