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.

TP-Link AC750 Wifi Range Extender | Up to 750Mbps | Dual Band WiFi Extender, Repeater, Wifi Signal Booster, Access Point| Easy Set-Up | Extends Wifi to Smart Home & Alexa Devices (RE200)
TP-Link AC750 Wifi Range Extender | Up to 750Mbps | Dual Band WiFi Extender, Repeater, Wifi Signal Booster, Access Point| Easy Set-Up | Extends Wifi to Smart Home & Alexa Devices (RE200)
Boosts wireless signal to previously unreachable or hard-to-wire areas flawlessly; Compatible with 802.11 b/g/n and 802.11ac Wi-Fi devices
₹ 5,499 ₹ 1,799
TP-Link TL-WA850RE Single_Band 300Mbps RJ45 Wireless Range Extender, Broadband/Wi-Fi Extender, Wi-Fi Booster/Hotspot with 1 Ethernet Port, Plug and Play, Built-in Access Point Mode, White
TP-Link TL-WA850RE Single_Band 300Mbps RJ45 Wireless Range Extender, Broadband/Wi-Fi Extender, Wi-Fi Booster/Hotspot with 1 Ethernet Port, Plug and Play, Built-in Access Point Mode, White
Miniature size and wall-mounted design make it easy to deploy and move flexibly; Easily expand wireless coverage at a push of Range Extender button
₹ 2,499 ₹ 1,299

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.