SOLVED
The keyboard type of the screen for the decryption of disk (pin or passphrase) changes : I need to type shift + number (on the horizontal line OR even on the number pad) both on my keyboard via web interface and via the virtual keyboard, contrary to what the virtual keyboard displays when I type !! Probably because the keyboard type of my pureos session is a french keyboard. I already had that problem some time ago even with the directly connected keyboard. So be careful if you use a different type of keyboard for your session.