Good to hear this is being looked into, it's seriously affecting raids and other in-game activities. A few things worth noting:
1)
Regarding this specific issue, players have the ability to login to the game, but the affected parties just rubberband/lag all over the place (possibly even D/C); it's the same with the website as well. Not being able to log in is not the issue.
2)
While I agree it doesn't hurt to let our ISP know about the problem, as noted from the numerous trace routes the bulk of the problems seem to be coming from NTT nodes. As such, there really wouldn't be anything that our ISP's can do regarding that issue. Had the problem been occurring on a COX node for example, then we would obviously be reporting to them to fix it.
To the best of my knowledge, NTT is being contracted by SE/FFXIV for their American services. This means that it would require SE tech support, whichever tier has the capabilities to do so, to open a request with NTT to look into the instability issues. I'm unsure whether or not these nodes can support the load they're carrying at peak hours which appears to be contributing to the problem.
I sincerely hope this issue can be resolved, because as noted, it's made in-game activities unplayable.
