If you're doing this on a mobile device, you have to simply keep trying. The last few days, I've noticed an issue with not being able to connect. Sometimes, I'll restart my iPad. While that seems to work, it could just be coincidental that it then connects after restarting the iPad.
It's a bit frustrating. But I don't know what the real solution is. It's fairly idiosyncratic as well. There are times I can't seem to connect with my iPad but have no trouble connecting with my iPhone.
You could start a ticket with customer support.