Ok, my network setup is so:

I have my modem connected to my router. I have one computer connected with a ethernet cable to that router. Then a computer upstairs is connected to that router wirelessly. My xbox is connected to the second computer with an ethernet cable.

How would I go about opening the following ports for my xbox:?

UDP 88
UDP 3074
TCP 3074

You need to find out what the network IP address of your 360 is on the network first. If it's the same IP as the computer it is connected to, then I can help you. All you do is go to start/run and type in cmd. When you are in the command line, type in ipconfig. The ip you are looknig for is 192.168.1.[3 digit number]. Take note of the last 3 digit number. You use this number to assign where the ports are being forwarded.

If the Xbox has a different network IP than the computer it is connected to... I wouldn't know how to find it, but it should be in the same format (192.168.1.[XXX]).

From then on you need to access your router's console. For most people you type in 192.168.1.1 in the address bar of any computer on the network, then log into your router (usually no username with 'admin' as the password). From there you look for any combination of "applications", "gaming", "ports", "range", "forwarding", and/ or "triggering". It should look like a link or tab.

When you are opening the ports, don't worry about naming them. Just open the ports to the right ip address. If you are opening a single port, use the same number on the "start" and "finish" sections of the range. For TCP set it to TCP. For UDP set it for UDP. If it is both (like your 3074) you set it to both. You don't need to make two entries for this. At some point it should ask you what IP address you are forwarding your ports to. Thats where you input that 3 digit number.

Right, I'll try that after work and let you know how it goes.

Thanks for the help.

Thanks for the help on the port forwarding, unfortunately it didn't work. When I typed in ipconfig, an ip address was there, but it did not end in 3 digits, just 1, so I'm not sure what to do.

I checked the IP address of my xbox, and it's 192.168.0.XX, and my router won't let me use that because it's not a "LAN IP address".

Any suggestions?

PS: Does anyone know if it would have anything to do with my computer connecting to a computer which then connects to the router wirelessly?

For anyone that has an xbox, I am trying to get my NAT status from Strict to Open.

Although Chainer implied it, the last digit of the ip adress does not necessarily have to be a three digit number.  The last number should be a number that is between 1 and 255  (most likely is a three digit number, but might not be).  Just use whatever ipconfig tells you and it should work.

As for your xbox, I'm not sure what it's telling you.  192.168.0.XX would not be a valid ip adress because it should end in a number that is (as stated above) between 1 and 255.   I don't have an xbox so I don't know about any setting like this, but perhaps there is a way that you can change the  value of that ip adress (I'm wondering if XX stands for something that you are to change by default when you set up your xbox for the internet?).

I can't help you. I only have experiance working with default settings with lynksys hardware... which is as stated above. I don't know why you would be getting those numbers... or how to fix them.

I've got this going on in my house. You would open the ports to the PC the xbox is connected to, then you would bridge the wireless and ethernet connections on that system. Make sure there's no software firewalls on that PC and you should be set.