Are you connecting to your home Wifi? or else where?

For Home Wifi - It's more likely the Router has something that the N900 cannot resolved. So reset the router to default factory setting and setting it up from little by little and connect it with N900.

This worked for me, in my case I can't get it to connect at all. It keep saying "......Failed, try again?" after reset router everything works

As for my University Wifi it has a bit of trouble some trying to connect as well. Keep saying "...Failed, try again?" but at one time I did a manual configuration editing it and it still say " ...Failed"..

So I keep trying and a few times later it works lol. It only work when I connect and then I go to Email. After it just say connected.

Weird.. but it work every time now. lol