A while back I started having problems hooking my cable modem to my Xbox360 and getting it to connect. I was told to change the physical address in the network settings of the 360 to match that of my PC and it worked a couple of times but no more.

Lately my PC is giving me problems connecting upon start up, after running the diagnostic it instructs me to unplug my router and modem wait and plug back in, this worked a couple of time but I haven’t been able to connect the PC for a week.

Yesterday I exchanged my modem thinking maybe it had died but still I cannot connect, any ideas?

The only things left to test are the cable connecting your PC to your router, the router itself, and lastly the NIC in your PC.

If all the above test out ok, then it's likely to an issue with your provider which means you'll have to call their support people.

Why are you connecting your 360 via the modem and not the router?

You can't do that and maintain a network thru the router. This is because the ISP usually only gives you one ip address and registers the pc's mac address to that ip.

This is why you had to change the physcial address [mac address] on the 360. You were fooling the ISP to think it was the pc. Just like you would do for the routers wan port.

I believe the solution is to do the proper connections modem<>router<>pc/360 and register the routers wan mac as your pcs mac [most routers have a "clone pc mac" option]. Make sure the router is configured as a dhcp server.

Connect a pc and lets see if you get internet. Then we can move on from there.

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The router is for my laptop connection and i don't want to spend $80 on a wireless card for the 360 as I only connect it to download demos.

What really puzzles me is it's been about 3 weeks since I even tried to connect the 360, my PC was good after that up until last Thursday, I didn't change any settings.

What is and how do I test the NIC?

Someone on a 360 forum just told me this, does it sound good?

The problem in these cases is most of the time caching of the IP address.

The simplest solution is adding a router between your modem and Xbox 360 / PC

If not possible make sure you release your IP address on your PC before connecting the cable to your Xbox.

To release the IP address

Start a command prompt and type "ipconfig /release" (without the quotes) and hit enter. Immediately disconnect your cable after the OK message appears. Connect the cable to your xbox and boot up.

Releasing the IP address on the 360 can be forced by testing the connection in the system settings

"The router is for my laptop connection"
what router model do you have? doesn't it have lan ports????? It should. You don't have to connect via wireless but wired.

"The simplest solution is adding a router between your modem and Xbox 360 / PC"

Kinda what I have been talking about above.

You certainly can try the ipconfig /release

Odds are your ISP changed the ip address you were getting which is normal dhcp ip leases.

No indication you need to test your nic [network interface card] from what you have written so far. A test would be to connect your pc to the router and see if you can access your routers web interface via the gateway ip. This is covered in the routers manual

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