My Cloud OS 5 Incorrect credentials, again, again, again

Hi. I have PR2100 and I updated the new OS 5. First all went well, but then something went wrong. The PR2100 started to work supeeeer slow. I reset the system to factory default. But now I have an abusurd problem. As I start the OS 5 and make a new password and press next… what happens? The system updates (several minutes), ok but after that I try to log in as admin with the new password the result is “Incorrect credentials”. They are not incorrect. I have done this procedure now at least 10 times, allways making a new password. And the result is every time the same; “Incorrect credentials”. No mater if it is done by WIN 10, MAC OS, Edge, Safari, IE…

I have no idea how to continue… How on earth can I log in if the system does not understand my password. I have done the 4 and 40 sec resets. Nothing helps…