Xbox 360 connection problems.

[#1]

My son's  X box 360 is connected via ethernet cable to a desktop pc then to the router via wireless network adapter, this system had worked for two years until the motherboard on the pc was replaced last week under waranty.
The router is a 3com and the settings on the network are:
Router IP: 192.168.1.1
S/Mask:255.255.255.0
Laptop IP: 192.168.1.2
S/Mask: 255.255.255.0
G/Way: 192.168.1.1
DNS: 192.168.1.1
Desktop PC IP: 192.168.1.3
S/Mask: 255.255.255.0
G/Way: 192.168.1.1
DNS: 192.168.1.1
Xbox 360 IP: 192.168.1.4
S/Mask: 255.255.255.0
G/Way: 192.168.1.1
DNS PRI: 192.168.1.1
DNS SEC: 192.168.1.1
The strange thing is that the router is not asigning an IP address automatically to the local area connection on the pc via DHCP so I entered the following settings manually for it:
Local area connection
IP: 192.168.1.5
S/Mask: 255.255.255
G/Way: 192.168.1.1
DNS: 192.168.1.1
When I run the live connection test on the Xbox it fails at IP address, I have also set IP and DNS on the xbox to automatic, but that throws up a completely different IP and no DNS.
I have contacted Plusnet via my questions and 3com and still not getting anywhere.
Any help with this matter would be appreciated.

[#2]

had same problem with using my desktops wireless like this. only had my xbox for 2 weeks,
1st i started using the ics way of using the pc's wireless but couldnt get an open nat on the xbox test and no joy with port forwading.
so then tryed the bridging way and that works only problem i have with the bridging way is that like your self dhcp dosent work for the xbox and when first switching the abox on i have to do a network test to get xbox live working for some reason but no big problem.
go to network and sharing centre, then to manage network connections, crtl click on botrh the lan and wirless then right click and bridge connections. Then make sure you can surf the web from the pc's if not delete the bridge an unplug the ethernet cable and disconnect from your wireless netowk then try bridging them again and connecting back to your wireless network.
Then i had to edit the network settings on my xbox by changing the ip to manual because dhcp did not work for me u might beable to still use the 192.168.0.4 on manual but my selff i gave my box .10 to make sure dhcop did not give the ip to one of my pc's on my network and use the subnet g/way u allready wrote. i left my dns on auto as that worked o.k but iam sure u know that is just your routers address.
then i just port forwarded 3074 and whatever the other port is to my xbox's ip and got an open nat.

[#3]

Hi there,
I'd certainly suggest having a look at the official support guides on how to do this, you can find them here:-
http://support.microsoft.com/kb/908885
They should point you in the right direction.

[#4]

Still no luck, I couldn't get an internet connection when bridging, think I may go with the hard wired option. Thanks.

[#5]

yeah when i first started to set my box up to use my pc's wireless connection i tried bridging first and kept losing my wireless network on the pc but with ics i could only get a moderate nat on the test so kept trying to get bridge to work and one day the internet was there when i tried. and what i wrote is the sequence of of bridging the lan and wireless adapter that finaly worked. it allso works on my laptop to.
if u can ethernet the xbox to your router then defo do so as with the xboxs wireless controler seems to interfere with the link speed of my netgear adapter goes from 54mb to 11 mb and back up all the time.
if i could afford to do so i would order a very long ethernet cable to run from one end of my house to the other as it cancels any lag issues u get from time to time on wireless. when i have got the monney it will defo be spent on ethernet cable and not the rip off microsoft wireless adapter.
have u tried the ics way at all?

[#6]

Can't believe I've got it connected. I tried ICS with the 3com router and it would not connect. I read on a forum tonight about connecting media centre on Xbox 360, so went along with the settings and managed to get the xbox to communicate with the PC. The gateway IP for the xbox was the same as the IP for the local area connection on the PC. I then ran test xbox live connection and got the IP confirmed, but DNS failed, felt I was getting closer, that's when I tried ICS. Before I was right clicking on the LAN network setting and selecting ICS, but this time I tried it on the wireless connection, then ran the xbox live test and it confirmed all. My BT1801HG router is now informing me that I have a third party router outside a router and this could cause a network problem, so it is recommending the third party pc be assigned to DMZplus, I am not too sure about this so will leave for now.
Thanks for your input.

[#7]

good hear u r up and running now.
what do u get on the nat test on the xbox as when i was using ics i had a moderate nat aand could not mange to do port forwarding on ics to get a open nat thats why i kept going back to trying the bridging method.
not 100% sure about the dmz but from when i was googling on how to get open nat on ics i came across this if i rember right ics acts as dhcp ect so its the ics that gives the xbox its ip and dmz is away of  say u have your xbox hard wired to your router and port forwarding still gives u a strict nat and u can put the xbox's ip in to dmz and this opens up the xbox ip to everything and the router does pretty much nothing on the firewall ect side of things for the xboxs ip. now i tryed this method but for certain reason i had to do it to my pc's ip the xbox was connected to which is risky as hackers love pc's ports but if u do this just to the xbox's ip your o.k as far as i know the xbox's ports r not targeted by hackers.
but like a say im not sure about..