I've been having lots of issues with the Dream Suite lately. I think it's on Nintendo's end. I always turn off the game and try again. It rarely happens to me twice in a row.
I'll second the having issues with the dream suite.
I've been trying to visit people's towns to get a look at villagers I might want in my town, tried it last night and it was on a good 5 minutes saying it was searching for a wifi connection....when I'm connected and can use it on my phone.
I think it's just an in game issue. I didn't bother to try turning it off to we if anything changes but I will next time
It will always take several minutes if your dream address has changed, so don't panic. If it's going on for ten minutes or something like that, then just flick your WiFi switch (Old 3DS) or run frantically away from your house (New 3DS) and everything should be fine.