SE say it's something outside of their control:http://na.finalfantasyxiv.com/lodestone ... ca8043daa3
This is another follow-up to the ongoing technical difficulties wherein players utilizing certain Internet Service Providers (ISPs) are unable to log in to North American data center Worlds, or are disconnected from the server.
Based on our investigations, there is a high likelihood that these issues are occurring at the North American upstream Internet Service Providers, which is affecting the internet pathways and resulting in abnormal connections.
Since these issues are not occurring within FINAL FANTASY XIV servers or data centers, we recommend that affected users contact their Internet Service Providers.
We will continue to monitor the situation closely, and we will provide more information as the situation develops.
[Date & Time]
From Oct. 26, 2016 9:30 p.m. (PDT)
・Players utilizing certain ISPs are unable to log in or are getting disconnected from the game.
All North American data center Worlds:
Suggesting it's one of the ISP backbones somewhere (e.g. Level 5).