unable to change WAN & other settings in Optronix GPON

Jammu and kashmir, India
Whereas I installed Bharat Fiber at my home and the vendor provided me Optronix ONU G/EPON single band. It was configured already when they installed. But whenever I login into the ONU as username: useradmin and password (as provided by the vendor), I can't change so many settings like IP addresses, can't see the optical power (Rx/Tx), can't change user name. Please help out, can anyone tell me what's the default admin and password of Optronix
Username: admin
Password: ONU@last 4 character of mac address printed at the back of modem
example: ONU@e5ad
The username for the WAN setting usually has the following format:

Take the first two alphabets of your name (given at the time of form filling ) + your std code (without 0) + landline number + _xcdr.
For example, the BSNL FTTH username of a person, whose name is Rahul, and whose number is 01282252177, will be

[email protected]

There could be the following possibilities for the XXX part:
North: ncdr / nid
South: scdr / sid
West: wcdr / wid
East: ecdr / eid

Contact BSNL or your LCO to get this information as they will have either created or configured the ONT.
The password is almost always the word password (lowercase).