Not very computer illiterate any help will be greatly appreciated

The first thing to check is if you are using a router, connect directly to the modem and see if it is then open. If it is then the problem is your router and you have to go online to your router settings and enable UPnP probably. xbox.com/networkhelp also has like twelve things to check

Sorry to bother you again how do I get to the online settings for my router. Sorry about this I'm terrible

read the manual, you usually have to enter an IP address in your browser that will connect you with your modems software. then you usually have to enter a username and password, most default modem/routers it's user:admin password:admin.

for example most D-LINK modems you type in your brower "10.1.1.1"
Netcomm it's "192.168.0.1"

So you need the right IP

As to change the settings it depends on the modem as your menus will be different to my menus.

What is the brand and model router you're using?

Google it and add in "open NAT for xbox" and you may find a guide for it.

I had to disable uPnP and add my xbox to the DMZ on my new modem I purchased today, the same as I had to for my old D-LINK DSL 502T

I'm with sky so I just have the router they supplied me with when I got my Internet. Thanks your help mate I will be sorting that out when I get home from work.

If you're having any issues finding anything via Google, just visit this site:

portforward.com

First find your router model (then you have to click through to get past their advertisement), then click Xbox Live 360 from that list.

This teaches you how to do port forwarding, but it's easier to just fix the IP of your 360, then DMZ it as Doomed Marine noted. However, not all routers have a DMZ feature, so you may actually have to forward your ports.

Ok mate all this help is really appreciated hopefully this explains why all of sudden I suddenly became **** at the games I used to be good at

very easy way i found out last week.... go to xbox dashboard....system settings.....network settings.....network configuration......move over right then go down to restore to system default. Then just sign back into xbox live.

Easy as that.. then your NAT will be open

Reseting your xbox network settings to default may not work depending on your router. Mine personally I have to disable upnp and port forward which means I have to create a static IP for my xbox. Not saying that wont work but it is not a for sure fix. Several methods include disabling or enabling upnp (can be done on your router settings or on the xbox), portforwarding, DMZ your xbox, etc.

Go to portforward.com and there you will find instructions for your router model and a step by step instruction on how to do everything.

Cheers,