in general it's better to extrude the "Grid" for have only boolean between volumes
and try to avoid "volumes to surfaces", auto-intersect volumes, ...

And maybe in your planar case it's more handy to extrude a surface first drilled by a grid...
because the method above take a long time process...20 minutes after no yet result!!!

Draw the planar Grid
Draw the surround planar perimeter
Select all
Make planar
Extrude