Linksys router's internet led always red

if your not able to connect then id try rebooting it all start with the modem then the router and your pc see if that helps and if nothing works it very well could be the modem

This is more likely a problem from the ISP` end. The adsl carrier is ON hence you see the DSL light ON but the internet light is OFF because the network is riding the TCP/IP packets which are to come on the ADSL link.

Inorder to sort this just catch hold of your ISP and they shlould reset your connector port on their network switch.