If you are renting a modem from your Internet Service Provider/ISP (Comcast, Astound, Cox, etc.), then having your own modem should reduce your monthly bill. Comcast and Cox ISPs won't need a service call.
Wired coaxial cable modem only (no WiFi).
Doesn't include WiFi Router or VOIP Telephone adapter.
(2) 2GBit ports
When new, this cable modem costs around $175+ on Amazon.
https://www.amazon.com/Netgear-CM1100-100NAS-Nighthawk-DOCSIS-Cable/dp/B01MXC4532
It comes with an A/C power adapter and a short BNC Coaxial Cable.
https://www.netgear.com/home/wifi/modems/cm1100/
Not compatible with Verizon, AT and T, CenturyLink, DSL providers, DirecTV, DISH or any bundled voice service.
Product Data Sheet:
https://www.downloads.netgear.com/files/GDC/datasheet/en/CM1100.pdf