Xbox Live failing at IP Address

[#1]

Internet?  Fine.  Hardwire the 360 into the modem?  Fail. 
I've been on the phone to Xbox customer support for an hour, who are stumped, and lead me on a merry dance of inputting different IP adresses, MAC addresses, reset factory defaults, etc, and it's still not working.  It doesn't work on auto settings, or user selected settings.  Plusnet tech support have not been any help, to be perfectly honest, either.  MS asked me to ask them is DHCP was turned on on my modem, which it is.  Is MAC filtering turned off?  Didn't seem to know.  What service name to use in the username and password section?  Not entirely sure.  And then fobbed me off to ring the modem supplier. 
What a brilliant customer experience for someone 1 day old with the service!
Can I ask if anyone out there hardwires a D-Link DSL320b to their Xbox and what setting they currently use?  I will love you forever.  And ever. Never had any problems hardwiring any modem before, and have 3 different ISP's.  I've tried everything.
*sob*

[#2]

I'm not familiar with your modem but does it have an Universal Plug & Play option (UPnP). Turning it on may help with the xbox set to auto.
You might also want to try using a 'crossover' ethernet cable to connect the 360 direct to the modem. I think I read somewhere that the one that comes with the 360 is just a 'straight through' ethernet cable and that if you want to connect direct to a modem, a crossover type ethernet cable would be required.
Other than that, you might have more luck buying a cheap router and connecting that to the modem and feeding the 360 and/or PC connections to that. If you can afford it and no other solution presents itself I guess buying a new combined modem/router would solve it but I guess you know that already 

[#3]

well heres the info u need to login into your routers setup pages. type 192.168.1.1  in your browser address bar then admin for both username and password. got this info from here [url]http://www.plus.net/support/broadband/hardware/dsl320b.shtml/url] as ive got a netgear dg834g.
Then check the things ms said like dchp and mac filtering as its not picking an ip add on auto these r the sorts of things to check so ms wasnt that bad it is hard to dignose problems over the phone.
As for cross over cables u should be all right with the standard staright though cable as i use staright though cable wired to router and wired to my desktop to use its wireless instead of paying big doallr for a adapter for my box both ways work fine.
if you cant get auto to work then set these your self on the xbox get the subnet and gateway info from your router. As your login address is 192.168.1.1 depending on how many comps u have set your xboxs at like 192.168.1.5 if you only have a couple of computers to make sure u dnt have ip conflicts.
subnet will be somthing like 255.255.255. but find this from your roter setup pages
gateway is your routers ip address so 192.168.1.1 and dns on mine is again same as my routers ip address so 192.168.1.1
just try and find your subnet from your router stats pages.
or another way to fibnd this info is to go to control panel on your comp and choice network and shareing then manage network connections then right click the adapter used on your comp to connect to your router and choice status then deatils. u should see all the info on subnet ect here
gd luck let us know how u get on.

[#4]

Can i ask what package you are on? I think you are talking about the modem that comes with option 1 and if this is the case then it's not suitable for gaming...

[#5]

whats it missing that makes it unsuitable for gaming?

[#6]

Not necessarily the modem, though with only 1 port it will be hard to track issues on a PC as you won't be able to see the admin screen when the xbox is on.
But Option 1 itself is not suitable for gaming, P2P etc, look at 2nd / 3rd bullet point up on here http://www.plus.net/residential/broadband/bbyw_option1.shtml

[#7]

Please try and use a pc or laptop first to confirm that the modem and your broadband are functioning. step by step in structions can be found here. http://www.plus.net/support/broadband/hardware/dsl320b.shtml
If this fails to setup. Then its your modem or broadband.
The other thing is when you are on your xbox settings page does the sbox show a green light saying conected ?
If it does not say connected then either you have a damaged network cable or a cross over cable is needed. the default one in the modem box is a straight through.
I did find my xbox network socket was rather finicky and got so feed up with making up leads and changing settings due to lag that i went wireless on the xbox. Made no difference to the laggy games. But thats another story.

[#8]

well with the lack of reply from the OP i guess they got the xbox running and havent pluged the pc into the one port on there modem since hehe