[Warfy]

how do i know my hidden ssid of cpe?

[pasnger57]

are you asking how would one discover what a hidden ssid is
... listens to a detected CH. of sed network with the right tool such a arimon-ng and stay on it as devices (in your listen range) connect that will beacon out the ssid

[ameen2020]

If we're talking about CPE. Just connect to it directly with cat6 cable and bypass the router. You should have direct access to it. Otherwise usually there's labels on most CPEs with port info such.
True words