Excitel Broadband provides high speed internet service via both ethernet and fiber service in many major cities of India. They plan of 50mbps, 100mbps , 200mbps , 300mbps and recently launched 400mbps in Mumbai city.
If you have plan of 50mbps then N range extender is enough however we by looking at neighborhood wifi congestion of N network in India N range extender is not recommended at all. It would give you problem unless yo live in farmhouse or far flung areas where next house is far away. But I doubt Excitel fiber would be available in those type of areas.
Now for 100mbps speed AC range extender is recommended AC750 is starting but for optimal speeds AC1200 is a good choice.
For plan above 200mbps a mesh router is recommended as AC1200 range extender won’t be able to cross 100-150mbps speed. You can use AX/Wifi6 range extender too but for get its full benefit base router also need to be a wifi6 aka AX router which I doubt Excitel is giving to its user. So better switch to mesh if 200mbps speeds are needed on repeater also called secondary node in mesh routers.