Don't forget the gateway is "beta". so theoretically you can't demand the same level of service as with the game. Too bad though, I think this feature is what makes the game stand head and shoulders above the other free-to-play MMOs
Considering the fact that the accessibility is quite random, I would speculate they are either constantly disconnecting/rebooting the gateway servers (related to the Xbox version going live?) or it's indeed a DoS attack.
I'm an avid Sword Cost Adventures player (I play it even more than the actual game...) I understand fixing such issues can take time but, seriously, almost 20 hours and it just seems to be getting worse.