Are you located in the US or somewhere closer to Japan? If you're able to connect to the NA data center and not the JP, it would seem that you may be closer to the US than JP in which you should always connect to the closest data center to you. Anything else is asking for trouble, especially with the recent upspring of DDoS attacks, that aren't really hitting FFXIV servers themselves, but the traffic nodes in between users and the data center. Please be aware that SE can't remedy the DDoS attacks on ISP nodes. They can only wait until they get bored and move on or until the ISP physically cuts the culprits cord.