I have my Optimus laptop with GTX 1060 and FFXI played fine with dgvoodoo2 but I still use my desktop computer to play.

FFXI uses DirectX 8 (like any other old games) which doesn't know how to call the Geforce dedicated graphics via Nvidia Optimus. There is no way to get it fixed unless you have to have dgvoodoo2 installed or downgrade your operating system to Windows 7 which has compatibility with Optimus.

Nvidia haven't solved the issue since then.
https://nvidia.custhelp.com/app/answ...ll-only-run-on