@Realme No, they don't give login through PPPoE. They give a static local IP to each customer (NAT). Then you need to login to their portal using your password and user id when you turn on your router, just as you would at your university. Every time you log in, you are assigned a public IP dynamically. 103.x.x.x IPs are generally on Airtel backbone, 115.x.x.x are on Airtel backbone. They also use Vodafone backbone in Kolkata (I'm not from Kolkata and have never used Vodafone transit.)
If you turn on Autologin, they bind the MAC of your router to your static NATed IP. The public IP doesn't change as they assign a static public IP to you and just map your static NATed IP to a public IP (which is shared by many others at your location). This public IP doesn't change frequently. I guess they manually need to change it. So, they change the public after 40-50 days or so. However, the ports are blocked.
POOR NETWORKING STRATEGY!!!
If you turn on Autologin, they bind the MAC of your router to your static NATed IP. The public IP doesn't change as they assign a static public IP to you and just map your static NATed IP to a public IP (which is shared by many others at your location). This public IP doesn't change frequently. I guess they manually need to change it. So, they change the public after 40-50 days or so. However, the ports are blocked.
POOR NETWORKING STRATEGY!!!