@Bherusingh 

Kindly refer to this troubleshooting guide to do basic checking

https://www.tp-link.com/support/faq/3032/

Then reboot back with some more details:

1. How often does this auto-reboot issue happen? When did it start to happen, since the purchase, or recently after some usage?

2. When it reboots, no devices can find its wireless network? How about the wired/LAN connection? Are you still able to get internet access when connecting a PC directly to one of the LAN ports?

3. Try to login to the web interface with the wired connection, then show us the Status page when there is no internet.

4. Who is the SIM card carrier?