Make/model of modem? Is this a modem/router combination (i.e. you have no separate router)? If you have a separate router, you should try connecting wired to this instead of the modem. You said it can connect to the modem, but it's not clear if you can actually see the UI. Are there any errors that you see via the browser or network connection settings?
If you can ping the gateway and it's going no further, I think a full factory reset of the modem is necessary and not just a power cycle, provided there are no other network appliances between your PC and the modem.
I'm working on an older Windows XP machine. 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.
Help?

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