The FLSun V400 3D printer with a new load of Klipper software requires some support files.
Instructions are posted to the wiki.
I would like to thank Guilouz for his excellent repository & wiki covering the upgrade of the FLSun V400. https://github.com/Guilouz/Klipper-Flsun-Speeder-Pad
Second person I would like to thank is phnxdrgn536 for his excellent repository which builds on top of information from Guilouz. https://github.com/phnxdrgn536/FLSun-v400/wiki