Is it possible to change the standard password on the ZTE F660 router (from promsvyaz)?

Question

network hardware

Good day!
question: a standard login / password is set on the router for telnet, I wanted to change it. The passwd command gives an error
An error occurred updating the password file.

permissions to access the file -rwxr-xr-x passwd

change permissions, but the system swears
/ # chmod 775 /etc/passwd
chmod: /etc/passwd: Read-only file system
/ #

is it possible to change the default password on the ZTE F660 router (from Promsvyaz)

Answer 1

On gpon terminals, this will not work, twist something there in telnet. The password is set either by the user from the web of the muzzle, or arrives from the provider. There is no third.