Does this sort of cable-screw => ethernet adapter exist?

The wireless router our ISP gave us is an awful Linksys, so I figured I’d buy one (since I have to pay per month for the one we have) and see if it works better. I bought an airport express that works great. The problem is, it doesn’t have a screw-on cable plug (that’s my term for this). So I’ve got the cable screwed onto the old wireless router, with an ethernet cable going to the new Airport Express.

What are my options here? Do I need to buy another router for the screw cable, or is there a simple adapter I can get?

There are two completely different things here: a wireless router, and a cable modem.

In the case of your LinkSys, both things have been combined into a single box. Your Airport is not a cable modem, it’s just a wireless router with some Ethernet ports. There’s no way to connect it directly to the cable, because it doesn’t have the circuitry for modulating a cable modem signal.

what you have set up is OK.

you need a cable modem for the cable you show to plug into, the cable modem could also include a router and it could be a wireless router. if you want it in one box use the Linksys or the same function in another brand. the

The only way to cut the Linksys out of the loop is to buy a cable modem. The signal coming off the coax cable is different from what is sent over the ethernet cable, so it needs to be handled by hardware. A simple adapter won’t do the job.

That said, you are probably fine with your current setup, because all you would be doing is trading the Linksys for a similarly sized cable modem. Not worth the money, imo.

E: You may want to price it out since I just noticed that you are paying a monthly fee for using the Linksys.

Check your ISP support website. They should have a list of certified modems like this one at CableOne.

Then just go online and check into some product reviews.