I'm working on an older Windows XP machine (but this issue is not limited to Windows XP, per #3 below). It can connect to my cable modem (gateway) via both LAN and wi-fi, but it can't "see" any further than that. Connecting to the Internet is a total no go. I can't ping anything further than the modem (gateway).
I've already power cycled the modem (gateway) released and renewed IP, flushed the DNS cache, rebuilt the TCP/IP stack, and re-installed all of the drivers. No joy. I still can only get as far as the cable modem.
Other information, since I was asked elsewhere:
1.) All of my other computers can connect to the Internet without issue through the same modem.
2.) I do not have MAC filtering enabled.
3.) Also, thinking it may just be Windows XP, I burned a (Puppy Slacko) Linux Live CD, but I'm having the same problem there.