Unable to connect to certain mobile apps on Wifi

Messages
3
Location
Chennai
ISP
Airtel
I recently purchased the Airtel Xstream Fiber and I notice that some mobile apps which were working flawlessly on the old connection have stopped working. The apps also still work fine when I switch to mobile data. Is there any router setting that needs to be updated?
 
Messages
515
Location
Barabanki
ISP
Airtel Xstream Fiber (300Mbps)
Jio Fiber (150Mbps)
Can you name those applications and games?
 
Messages
22
Location
Bangalore
ISP
Airtel
I'm also facing similar issue with few mobile apps like Bigbasket, Paytm and whatsapp.

Whatsapp status won't load when i connected to Airtel fiber wifi. It works on mobile data.

Tried turning off Firewall on Router.

Also changed the dns to Google dns and cloudflare dns on Router > Network > LAN

Tried to change ipv6 dns. But i was unable to change the ipv 6 dns.

Any fix for this?