2fa does not work with my firefox 64 bit version 58.0.2 in combination with Facebook. The settings in Facebook say that browser firefox does not support u2f, with usb-keys, such as the Yubico nano.
To use the option below: 'Use a User Agent switcher to identify as chrome to websites', I don't understand. Maybe someone will explain this in this bloc. Ruud 8-2-2018