The Fritz!Box Standard Firmware is factory installed but it is strongly recommended that a check for UpDates is made at the earliest possible time.

This is a work in progress, but meanwhile please visit:

Fritz!Box BETA [or Lab] Firmware Installing

The directions there can be followed as a guide, just be sure to work with the correct Fritz!Box Firmware current for your product.
NB. The Beta [or Lab] Firmware does not function with all Fritz!Boxes.
No attempt should be made to install Beta [or Lab] Firmware on hardware that it has not designed to work with.