Xbox Series X Game Pass & Microsoft Store not working on BSNL broadband, works perfectly on mobile hotspot

Hi everyone, I’m having a strange network issue with my Xbox Series X.

The Game Pass launcher doesn’t open properly / gets stuck on the spinning loading screen, and the Microsoft Store is also not loading properly.

What’s confusing is that everything works perfectly when I connect the Xbox to my phone’s mobile hotspot. Game Pass and the Microsoft Store open normally without any issues.

My setup:
Xbox Series X
ISP: BSNL broadband
Tried Wi-Fi and also Ethernet/LAN directly to the Xbox
Game Pass launcher: stuck on spinning/loading
Microsoft Store: not loading properly
Mobile hotspot: works perfectly

I’ve already restarted the Xbox and tried a few basic troubleshooting steps, but the problem persists on BSNL.
Could this be something related to BSNL DNS, NAT/UPnP, IPv6, or routing to Microsoft/Xbox servers?

Has anyone in India, especially BSNL users, experienced this recently? Any recommended DNS settings or BSNL router settings that fixed it?

Thanks!