@Swarna 

Can you get internet from the  jiofi model m2?

What is the current operation mode of the TL-WR840N? 

I searched online and found that  jiofi model m2 is a 4G mobile router, if you want to use the TL-WR840N to boost the wifi, you can configure it as a range extender. 

Instruction attaches as below: 

1. Login to the web UI and go to operation mode page to change it to range extender mode. It will reboot to apply the settings.

2. Go to quick setup to configure it.

Note: Please use the main router's wifi password to configure it. 

Good day.