Daily 90006 errors here as well. Lagspikes & rubberbanding leading to disconnect, 'character already logged in' and having to sit through the queue again, every time.
Mostly either in combat or interacting with NPCs that need to either trigger a cinematic or bring up a menu (such as teleporting).
Have nearly died and actually died, because of it. Even during crafting, which loses you materials if you disconnect.

On Primal Data Center (Lamia) or Crystal (Balmung).
The issue is the same, so it might just be NA servers in general.
Have tried every troubleshooting tip as well (aside from VPN, since it sounds a bit silly to have to resort to essentially paying a third party program to make the game playable).