AT&T customer here. I have U-Verse, not fiber, as many on here have stated they have, but the problem still exists. I am in South Louisiana.
Very disappointed in the lack of updates on the progress of their efforts to resolve this.
I have unsubbed for now. I am not spending my money if I can't play without frustration. Characters appear to run, stop, dart forward, stop again, rinse and repeat. Skills hang and then speedily go off. Enemy skills/attacks cannot be avoided because they go off before there are even any indicators.
Might try the VPN Alajandria mentioned above if NTT, AT&T, AND SE can't get this sorted out soon, but, I have never found it necessary to use a VPN and do not relish the idea of using one just to play a game I have been playing all along (since release) without one.