OK...I think you're doing something wrong
You need just one cable incoming from the street for your router.
A router is made by a company like Linksys - you buy it at your local store and you plug the Roadrunner cabel into the back of it.
Then you run either cables from it or better yet - get a combo wireless/hard cable router
The IP address will then be something like 192.168.xxx.xxx
Do you have all of the above so far?????
It WAS working when using a wireless adapter from one computer upstairs, but when I took the adapter out for the computer upstairs...the next day when I connected the wireless downstairs it went to 169.00 IP and I can't even get a connection as wireless.
The strange thing is that last summer it was hooked up exactly the same and worked.