Yes, it's 5g band, i tested with Ethernet also but it remains at 25 fps. I also tested with other ISP of 400M plan without any luck. It's not the speed issue. For testing, I upgraded the hotstar plan to 4K premium with the same registered mobile number, this time it streams at 4k with 25fps instead of 1080@25fps. Since everybody claiming they are getting 4k@60fps with the default plan I changed the registered mobile number to another number now I'm getting 1080@25fps.
Device Model : JMSB200A
Version & Build : Jio 2.0 JioSTB-JMSB200A-19.1.10