SOS Cant resolve the issue wireless not working

Got the same problem here!

Try this troubleshooting document and see if it resolves your issue.

support.xbox.com/.../error-cant-connect-wireless-network-978945

We did reset the modem when switching to the new router. It didn't seem to change anything. We have tried DMZ and in network settings we switched the DNS to a manual setting instead of automatic, and even then it has not helped. We connected my brothers
original Xbox 360 to the network and it works just fine, so it is definitely the xbox. And although I could "just use that xbox" it frustrates me because it's a smaller hardrive and all of my game information such as saves and profile data is on the slim.
And i am not going to buy a 250GB hard drive for the original when i already have one. Sorry, I am not trying to sound mean this is just what I believe. It is a good thing for cloud storage otherwise i would have to use a USB to move the data. While this is
a convenient solution, I would still like to have the Xbox fixed as it is preferred over the original one. I was hoping it could have been a problem I could mend on my side, but it looks more and more like I am going to have to send it in. Unless there are
any other suggested steps, I might have to wait a few months while I save the money for the repair. But I do want to thank you very much for responding to my posts and helping me out in the best way you could. I appreciate that very much.

Hey Lando, I'm really sorry to hear about the connection issues! Okay, based on your post, I'd like to see the results of a
connection speed test and
ping test. Can you please post the results for both here? Also, I see you've been a member of LIVE for 5 years--when did these issues begin?

Hey Lando, I must have missed that the console isn't allowing you the option to choose wireless at all--that definitely indicates a hardware issue. To determine if the issue is affecting only wireless or if it's also the cause of these wired-in issues, there
are a couple things to try next. First, can you try connecting directly to the modem? This will allow us to ignore any settings in the router for the time being. If plugging into the router (after resetting it, of course) produces the same results, then we'll
have a pretty good idea that the Xbox 360 console will need to be repaired. Also, be sure to test a couple cables, just to be sure.

However, if the console connects in that state, we still have a few more options.