I have tried both of your suggested ways to access modem to do the update & the only way to log into my hg659 is by using vodafone/ vodafone as user name & password
have you tried:
@Admin and then the last 8 digits of your SN number on the back of your modem? this does depend on what version of firmware you have.
Yep have tried all the possible combinations mentioned in this thread, I see someone did a factory reset of the modem & the super admin username/password mentioned in this thread. Might try a reset on modem to see if that works.
Did a reset of modem & all is good now. Am able to do firmware upgrade after reset using username "Admin" * password "@ last 8 digits of serial number