This has been happening to me either at random or on specific days for certain events. I'll either be world hopping no problem or hangout in once instance for an hour or so. After I'm done and want to go say hi to certain friends, or go to an event, I'll join the instance, it takes forever to connect and upon joining I'm met with the connection timeout screen.

If I keep clicking "Okay" and trying to reload the instance, I'm stuck in a loop. Yet when I go to make my own instance of that same world, or just join ANY other instance, I have no issues at all. Been frequent this entire month for me.