Router is calling an address every 3s

The issue I am facing: is being called by my router every 3 seconds for the last 3 days since I installed pi-hole and discovered this address.

Anyone has any clues on what this address does? Googling is not helping. Accessing the URL doesn't help me much either.

Details about my system:
Router: Totolink a3000ru v2
What I have changed since installing Pi-hole: