You raise an interesting question but the simple and reasonable answer to me is if that the iPad reads the @ symbol as the end of any line of text, you would not be able to use any email addresses on the device. Does this make sense? I have never read of that with regard to the iPad.
There could be many reasons why you can't connect to this point. Did you try to reboot your router and cable modem....unplug for about 30 seconds and then plug in again? Reset Network Settings ... settings>general>reset>reset network settings? You will have to re-enter the password if you try this.
I find that more often than not, my problem is that I am simply mistyping my password when I have issues similar to yours. The freaking password has about 150 characters and symbols and inevitably, I screw it up a few times before I get it entered correctly.