NUKI 4 pro Firmware 4.2.8 update Connection loss

On April 19, the new version of the firmware was installed.
The lock connects using a bridge that it shares with an old and stable 2.0 without any problem.
Since the update the connection has been lost, it is inaccessible from the app, close access via Bluetooth or remote access via WIFI is not possible, nor does NUKIWEB connect.
It only starts working by removing the batteries.
It is installed in a tourist apartment, this weekend I had to go 3 times to reset the lock, a client on the street in the wee hours of the morning.
It is not possible to change to a previous version of the firmware, which would solve the problem at least urgently.
One funny thing is that a person is staying here who wanted to play with the lock with a view to installing it on his properties in Canada, what a brand image.
The constant errors of these devices are beginning to make noise in some forums of both AirBNB and Boking.com
Frankly, I think they are shooting themselves in the foot.

Please enable downgrade of Firmwhare versions that do not work.

Clients and especially professionals are not beta testers and NUKI 4 is a beta that should never have gone on sale (well, NUKI 3 neither)