Is this the ISP wifi device?
YOu mention running the Ethernet cable from the WIFI to the router. Take that cable, and attach your laptop, instead of the WIFI device. Do you connect? IF so, then you need to run the installer on the WIFI device. If you do not have the installer for the device, then you will need to completely reset the device. I suggest going to the WIFI device manufacturer support page, and following directions.
If you connect an Ethernet cable to your ISP gateway, and you don't surf, caoll your ISP!