360S console needs WEP key when I'm using WPA2

Ok well if you are not sure if you are using WEP or WPA its likely your not using the correct WEP key or WPA passphrase, you need to access your routers menu via
http://192.168.1.1 and find out those details

If all your wireless support WPA2 I would recommend using WPA2 AES security

Are you sure that the router does require a WEP key instead of a WPA2 or other alternate password? If you're trying to log onto a WPA2 protected network by entering a WEP key it does this at times. This can be changed in Network Settings on the home screen.

This console supports WPA / WPA2, WPA2, and WEP security protocols, but the router uses a different system. You need to change the router configuration.

It's the message when I have write mi SSID

Right, I've done a bit more testing. The following options work:

Open.

Wep with shared key.

The following don't:

WPA

WPA2

WPA/WPA2 Mixed.

:/

It connected fine using WPA/WPA2 mixed on Saturday, but not now! Obviously running it on WEP is just as bad as having it open!

Thanks for help so far.

Are you referring to WPA2 for your security? The Xbox 360 console only supports WEP, WPA and WPA2 for network security.