Modem for tv/internet

Are you talking about streaming to a smart TV or box similar to Roku?  Or receiving Cox cable on your TV?

If you want to receive cable tv, you don't need a modem, but you may need a settop box.

If you are setting up streaming service, you need a modem approved for the level of internet service subscribed to.  See here.  You can either choose a gateway (modem/router combo) or separate modem and router.  Streaming Netflix in HD requires about 6Mbps bandwidth, 4K requires more.  You may be able to get away with Internet Essential which gives you 15Mbps but a cap of 250GB/mo.  You may have to go up to a higher plan depending on your usage.