Unable to log into Airtel AirFiber router (AAP321NK) admin page — invalid credentials error. Any fixes?

Recently, I got a new Airtel AirFiber connection. I know it's far from ideal, but the area I moved to doesn't have feasibility for Airtel Fiber, Jio Fiber, or ACT Fiber, so I was forced to get it.

​I need Wi-Fi coverage across two floors, but the router provided (model: AAP321NK) barely reaches the 2nd floor, and when it does, the speeds drop drastically.

​I have an old Nokia fiber router (model: G-2425-A) from my previous connection that I'm trying to set up as an Access Point / Mesh router. To do that, I need to check if the main AirFiber router supports mesh or bridge mode. However, when I try logging into 192.168.1.1, the username and password printed on the back label don't work (gives an "invalid credentials" error). I've also tried common defaults like admin/admin and admin/password with no luck.

​Has anyone encountered this issue or found a solution/working credentials for this specific model? Any help would be appreciated!