That might be the cause then since the DS4 doesn't work well on windows without an emulator.
I've know them to have disconnection issues when using bluetooth and wired at the same time eg. Your using bluetooth but the battery is low, so you plug in the usb cable and play. It will then randomly disconnect. Sp id your battery starts dying you need to close FFXIV, disconnect the controller by pressing PS & Options, then plug in the usb. Or just use wired the whole time.
I wiuld recommend installing either DS4windows or Input Mapper.