Well I can't make a post so this is all I got,What kind of modem do I need for an Archer c1200? My current router,Air router doesn't seem to have one?I'm very confused with that, Any hopefully you can help!
If you currently have an internet connection, then you already have a modem since the modem is the interface between the ISP and your home/office. A router allows you to connect multiple devices to that same connection.
Are you saying that your current modem doesn't have a built-in router? That's a very common situation. Usually the modem has an Ethernet cable output that you can then connect to a router (such as your Archer).
Can you post a picture of your current setup so that we can better understand what you are trying to do?