Update: As mentioned by @salaxzar my internet (after 5 days) has now started functioning properly with the same router which was deemed faulty the LCO. So in case any of you other excitel users have the same problem waiting it out seems to be the only option.
I seem to have a very similar but even more peculiar issue.
I have 3 routers.
1. TP-Link TL-WR720N (2.4ghz) router (old router, stopped using because it's max wifi speed is 35-40 mbps)
2. D-Link DIR-816 (5 ghz Dual Band) (bought it last year to replace TP-Link router
3. Netgear R6080 (5ghz Dual Band) (bought it yesterday)
Been using D-Link Router since June Last year and it was working properly and I was getting around 90 Mbps on both Lan (desktop) and Wifi (5ghz). (apart from usual excitel connectivity issues).
Started facing intermittent connection issues a few weeks ago and 3 days ago they asked me to reset my modem. Which I did. After the reset, and reconfiguration of Router I only get 9 Mbps download speed and around 14 Mbps upload speed.
I called Excitel customer care and they said that my router is faulty.
I called D-Link customer supoort, and they tried everything from firmware update to firmware flash and still I got 9mbps speed. So they said might be something wrong with the Router and asked me to take to service center. But service center guys refused to accept it as I had misplaced my bill. Okay. Done and dusted.
Ordered a new router yesterday and received it today. It is a NetGear R6080 Dual Band Router. After I set it up, funny thing happened. I'm getting 9 Mbps on this new router as well! I contacted Netgear customer service and they updated the firmware and did resetting and still I'm getting 9Mbps.
What is weird is that the oldest of the 3 Routers, TP Link (2.4Ghz 150Mbps) Router is giving me 90Mbps on Lan (Desktop) and 35-40 Mbps on Wifi.
But newer and more advanced Routers are giving me 9Mbps. I have tried everything, including scratching my head for hours. Still no clue why this is happening.
@Sushubh I had already talked to the customer service yesterday about MAC binding, and they said that they don't use this method. I'm kinda inclined towards that answer too as that would mean only the MAC binded router will work and no other. But other routers work, but not how they should. Even the router that used to work before perfectly (D-Link) with 90 Mbps speeds is not working properly anymore as it's also giving 9Mbps. So seems like a configuration issue at the server side.
Something that only the TP-Link router is able to demodulate properly.