I have an archer C50 V3 
I'm trying to use this router to extend the range of my wifi network, provided by airtel. I am not able to see operation mode to set the router and an access point to extend the range of the router. The archer c50 has been connected to the router by the metwork provider through a LAN cable and I acess internet through my tplink router only. Does this mean the router already acts as an extender? As no Wds setting have been configured. Need help with setting this as an extender.

Thanks