Connecting to Internet wired through a Coax?

Can I connect to the internet via ethernet/coax?

I have a desktop PC in my office that struggles to pick up the wifi from our Surfboard modem/router in the living room. The modem/router in the living room is connected to a coax and there is another coax in the office.

I had the modem/router connected to the coax in my office initially which worked, but then our TV struggled to connect consistently, so we moved it.

Any solutions for a wired connection in the office?