No internet connection on 360s, tried everything!

Same This just started today for me when I go to Set up wireless network nothing even pops up And when I add network it doesn't support the security of it anymore which makes no sense it did yesterday and my brother has an Xbox as well on the same Wi-Fi
and he connects just fine So like what is going on.

If you are using a wired connection using Broadband Extenders (Flex for me). I would suggest re-connecting those as you would when initially pairing them, holding the link button for 5-8 seconds, wait for the steady light, then again for 1 second, then go
to another Extender plug and press that Link button for 1 second. Then plug in the ethernet cables to the xbox and Extenders again.

if you are wireless i would suggest completely powering down the xbox and unplugging all cables. Hold the xbox button on the console for up to 10 seconds and wait for it beep and shut off then un plug all the cables, wait 5 minutes then try again. If nothing
i really am not sure of anything other than resetting your router at the same time as doing this.

Hello! I'm aware that your internet connection seems fine, but have you tried restarting your router? Just to be sure.

- Jesper, Ambassador.

Sounds like your college internet is blocking Connection to Xbox Live. I recommend going and talking to tech support at your college about it. Sadly it is the Holidays so you may have to wait until Monday to discuss this with them.

I remember in the dorms, when I did something similar, I had to go to the IT website for my university and input my console information so that the server would accept its access. It's similar to like if you registered your laptop through the school's network.
Try checking out the school's network site.