How to use "Beetel 450 BX1 ADSL Wifi Modem" as just Wifi Router/ Range Extender?

Hi to All,
This is Pravin, New Member of IBF.
I am just learning things on Trial and Error Basis.
Let me get to the point.

I have an old Beetel 450 BX1 Wifi Router modem with me. Currently I am using TP Link N300 Modem + Wifi Router. The reason I bought TP Link was to Extend the range. The range of TP Link is same as the Beetel Modem. It's unfortunate. I want to use my Beetel modem as Wifi Router to extend the range. I tried various things, it's not getting connected to TP Link. I disabled DHCP, assigned same default gateway, same Subnet mask and Assigned DNS IP of TP Link in Beetel modem.. Nothing happens. I know somewhere I am missing something, it's messing the whole process. Since I am not very experienced with WDS/ Bridging, I am in need of your valuable guidance. My Last hope.
Beetel Modem Interface is little confusing for me due to my inexperience.

I request you guys to give me detailed instruction, if you know any.

Thank you

With Hope,

Pravin

I dont know much, but from what I know I think your missing a repeater which would connect to the WiFi connection, hence extending the connection.