Changing the default password on the router HUAWEI HG658C is pointless when:
1) There are undocumented accounts on the router.
2) You don’t have the password needed to log into the account to change the password!
Here is a table of the three usernames and passwords that allow logging into the web interface. The “vodafone” username is the basic account, “superuser” allows full access and “admin” is somewhere between the other two.