That's just a router. You still need your own modem to send theirs back and stop paying fees.

I have gigabit xfinity so I bought an approved xfinity modem.

If you don't have gigabit you don't need a modem that supports it.

What's your current plan? The modem you buy should support speeds that high. Getting a gig modem would help you be future proof if you don't already have a gig plan.

NETGEAR Nighthawk Cable Modem CM1200 - Compatible with All Cable Providers| For Cable Plans Up to 2 Gigabits | 4 x 1G Ethernet Ports | DOCSIS 3.1, Black (Renewed) https://www.amazon.com/dp/B08HY7KRPT/ref=cm_sw_r_apan_glt_fabc_H2NE8CVC3MNT67Q1RTER

NETGEAR Gigabit Cable Modem (32x8) DOCSIS 3.1 | for XFINITY by Comcast, Cox. Compatible with Gig-Speed from Xfinity - CM1000-1AZNAS (Renewed) https://www.amazon.com/dp/B07ND1PQMS/ref=cm_sw_r_apan_glt_fabc_TZM1JA6XKPW9SAQRZY8C