The dd-wrt firmware is installed in the router. I can able to ssh/telnet to the router also I can able to snmpwalk to the router. How to get router temperature using SNMP or CLI (ssh/telnet) which is shown in web GUI?
Finally I found the way to get temperature of the router via CLI
cat /sys/class/i2c-adapter/i2c-0/0-0028/temp_input