How get supervisor od root password of NR7103 modem?

Hello,

I have a Zyxel NR7103 that was originally supplied by O2 Slovakia. The original O2 contract has already ended, and the device is now privately owned.

The device label does not contain any admin/login password, only the Wi-Fi key.

I have already tried:

admin / 1234, admin / Wi-Fi key, user / 1234, user / Wi-Fi key

None of them work.

Could you please provide the admin password for my device?

S/N: S220Z41007283

Thank you.