How can i access my extender router?

I have my main router connect to extender wifi via lan cable
but i can't access my extender router ( setting via main router

Please copy the output of the following commands and post it here using the "Preformatted text </> " button:
Remember to redact passwords, MAC addresses and any public IP addresses you may have:

cat /etc/config/network
cat /etc/config/wireless
cat /etc/config/dhcp
cat /etc/config/firewall