Firstly
Do not confuse modem and router

Modem, also known as BTU or ONT, is the one that takes the fiber and converts it into an Ethernet Port for you to connect your router to

The router is the one who handles all the network connections and also gives you your WiFi

On newer setups, they give you a 2 in 1 device, that combines both into one

If your modem is faulty, call TIME and get them to replace it, free, lifetime warranty

If you want a new better router, firstly, what's your current router to compare with
But for like 200 to 300, maybe consider a TP-Link AX53?

2in1 ones are not generally available for general public
you could buy a 2nd hand time provided one or recontract to get one
but it's not worth it to recontract and 2nd hand ones require advanced configuring

and even then, most prefer modem + router seperate as it gives you more freedom to choose your own router

keep the time provided modem and use a router that you like

Assuming you are on old
modem + router 2 device setup

remove old router
plug new router, connecting from LAN 1 of modem to WAN of router
login to time self care portal and get PPPoE username and password
enter those into new router setup
done